2^nd International Conference and Exhibition on Mesoscopic and Condensed Matter Physics October 26-28, 2016 Chicago, USA

Biography:

Dr. Quan-Fang Wang is awarded the master, doctor degrees in Systems and Computer Sciences, Mathematical and Material Sciences at Kobe University, Japan, on 1999 and 2002, respectively. Via research work in Chinese Academy of Sciences, she worked at The Chinese University of Hong Kong 2004. Dr. Q. F. Wang had published books Optimal Control of Nonlinear Parabolic Distributed Parameter Systems;Practical Application of Optimal Control Theory; Optimal Control for Cahn-Hilliard Issues; Identification in Inverse Problems. Dr. Quan-Fang Wang is included in the Marquis Who's Who in the World 2011 (28th edition), 2014 (31st edition) and 2015 (32nd edition

Abstract:

Bose-Einstein-Condensates (BEC) had been investigated in the fields of particle physics for a long time. Quantum control of BEC has already been considered in the theoretical, computational, and experimental aspects at a great deal literatures and contributed papers. The discovery of gravitational wave at the years 2016 could be verified the prediction of Einstein many years ago. Very naturally, in the presence of tiny vibration of time and space, what will be happened for particles condensates? Whether needing to suppose that the gravitational wave would be sufficiently small or large to influence the BEC status? otherwise, there is no influence at all for creating a BEC? The vibration of time and space should be caused by particle mass itself? or mass of other objects? All of these questions are interesting and still be mysteries. In this work, we try to consider quantum control of BEC if there exists the vibration of time and space, which caused by gravitational wave, the mass of matter. Theoretic quantum control of of vibrated BEC will be reported. Numerical and experimental works is left to future.

Biography:

Marius did his studies at the University of Bayreuth and received his PhD there this year at the age of 30. This month, he joined the Soft Matter and Neutron Scattering Group at the Louisiana State University for postdoctoral research.

Abstract:

NMR relaxometry provides rich information on the dynamics in complex liquids, such as polymer melts. Using the field-cycling (FC) technique, the spin-lattice relaxation rate R₁ , reflecting the spectral density, can be measured over a broad range of frequencies ω, appreciably reaching below the earth field, with sophisticated low-field equipment. Assuming frequency-temperature superposition, the effective window extends about ten decades in the NMR susceptibility representation c’’(ω) := ωR₁(ω), when master curves are constructed. In high-M polymers, the local (a-process), Rouse and entanglement dynamics is covered. The broad frequency range allows for a transformation into the time domain; a time auto-correlation function is gained.

Concerning ¹H, relaxation is caused by fluctuations of the dipolar interaction, comprising intra- as well as inter-molecular contributions. The isotope dilution technique allows for a separation yielding both, the re-orientational correlation function C₂(t) as well as C_inter(t), providing the segmental mean square displacement (MSD). Complementing the FC data with such of field-gradient NMR reaching even longer times, the full MSD is probed in highly entangled polymers. All power-law regimes of the tube-reptation model are reproduced. Concerning C₂(t), however, the predictions are only confirmed in parts. Comparing FC NMR with shear rheology, much similarity is found, regarding the local, the Rouse and the terminal regime. This renders FC NMR as a powerful tool of molecular rheology. As NMR relaxometry addresses molecular correlation functions, the slow dynamics in the entanglement regime is resolved. In particular the constrained Rouse, the reptation regime as well as the corresponding crossover times. In contrast, the shear data is governed by the rubber plateau

Biography:

Michael W Roth is a computational Physicist and Professor and Chair at Northern Kentucky University’s Department of Physics, Geology and Engineering Technology. Dr. Roth has numerous publications and presentations in the field of dynamics and surface phase transitions of atomic and molecular systems adsorbed onto graphene and graphite. Other interests include classical astrophysical simulations of planetary formation as well as Material Point Method simulations of impact and material stress and failure.

Abstract:

Nanometer – scale systems exhibit rich, interesting and novel behavior when adsorbed onto surfaces, in part because the species are confined and also because the adsorbate species interact more strongly than in the bulk. Organics such as pentacene, alkanes and fullerens on graphene and graphite exhibit a wide variety of epitaxy, phases and phase transitions that are of fundamental scientific as well as technological importance. This presentation will provide an overview of Molecular Dynamics (MD) simulation techniques as well mathematical characterization of the various phases and phase transitions realized by these fascinating systems.

Biography:

Myung Joon Han has completed his PhD in Seoul National University. After spending five years of postdoctoral studies in U. C. Davis, Columbia University, and Argonne National Lab in USA, he joined KAIST as a faculty member. He is now an associate professor of Physics and also of KAIST Institute for interdisciplinary research.

Abstract:

Artificially-structured oxide superlattice is a fascinating playground for the new material functionality originated from strong electronic ‘correlation’. When the conventional bulk material becomes 2D-like, the intriguing ‘correlated phenomena’ can emerge as a result of cooperation between the spin, orbital, and lattice degree of freedom. As one typical example, we present our calculation results on the nickelate superlattice, LaNiO3/LaAlO3. Based on the first-principles density functional theory calculation combined with the state-of-the-art ‘many-body’ techniques, we examined the possibility of unconventional superconductivity and emerging magnetic order in the thin LaNiO3-limit. The dynamic as well as static ‘correlation effect’ has been analyzed and the results are compared with recent experimental reports.

Biography:

Leonardo dos Santos Lima has completed his PhD at the age of 31 years from Universidade Federal de Minas Gerais - Brazil and postdoctoral studies from Tecnische Universität Kaiserslautern, Germany. He is professor of physics of Departamento de Física e Matemática Centro Federal de Educação Tecnológica de Minas Gerais. He has published more than 25 papers in international journals .

Abstract:

The progress in the investigations of Spin Supercurrent and magnon BEC was recently described in the review [1]. Particularly there was overviewed the spin supercurrent Josephson Effect which is the response of the current to the phase between two weakly connected regions of coherent quantum states. For quasiparticles such as magnons and excitons in Bose-Einstein condensation (BEC), it demonstrates the interference between two quasiparticles condensates. Spin current as a function of the phase difference across the junction, α1−α2 , where α1 and α2 are phases precession in two coherently precessing domains. It is the response of the current to the phase between two weakly connected regions of coherent quantum states cite{YuM}. It was described by Josephson in [2]. We use the SU(3) Schwinger's boson theory to study the spin transport properties in the twodimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: 〈t z 〉=t . Our results show a metallic spin transport for ω>0 and a superfluid spin transport in the limit of DC conductivity, ω→0 , where σ(ω) tends to infinity in this limit of ω. [1] Yu. M. Bunkov, G. E. Volovik, Novel Superfluids, eds. K. H. Bennemann and J. B. Ketterson, Oxford University press, arXiv:1003.4889v3 (2013). [2] B. D. Josephson, Phys. Rev. Lett. 1, 251 (1962).

Biography:

Oomman K Varghese is an Associate Professor in Department of Physics at University of Houston. After receiving PhD degree in 2001 in Physics from Indian Institute of Technology Delhi (IITD), he worked as a Post-doctoral scholar in University of Kentucky and also in The Pennsylvania State University. Later, he was employed as Chief Scientist at Sentech Corporation, Pennsylvania and then as Development Engineer at First Solar, Ohio. In 2011, Thomson Reuters ranked him 9th among ‘World's Top 100 Materials Scientists’ in the past decade. In 2014 and 2015, he received the title ‘Highly Cited Researcher’ and had his name listed in ‘World’s Most Influential Scientific Minds’.

Abstract:

Functional materials change specific physicochemical properties under the action of external stimuli such as light, electric field, magnetic field, temperature, pressure or atomic/molecular interaction and this behavior makes them highly relevant both scientifically and technologically. Oxide  semiconductors such as titanium dioxide and zinc oxide belong to this category. These are earth-abundant and low cost materials useful for a wide range of applications including electronics, optoelectronics, photovoltaics, photocatalysis and chemical sensing. Nanoarchitectures of these materials exhibit unique properties and as a result, a number of methods have emerged for developing them. Anodic oxidation is a century old industrial process
traditionally used for growing protective oxide films on metals such as aluminum and titanium. The process is currently known primarily for its ability to yield highly ordered one-dimensional nanoarchitectures such as nanotube and nanowire arrays. Titania nanotube array architecture has already been widely explored for various applications including solar energy conversion. Recently, a zinc oxide nanotube-nanowire hybrid structure developed using anodic oxidation exhibited promising characteristics for use as chemiresistive sensors for early non-invasive detection of breast cancer. This talk will focus on the specific properties of these oxides for applications in energy conversion technologies such as hybrid solar cells and solar fuel generation processes as well as in clinical devices for early detection of cancer.

Biography:

S N Pandey has completed his PhD from Avadh University. He is the Head of Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, India. He has published more than 35 papers in reputed journals. He is recipient of UGC Research Award and many visiting fellowships. He is Life Member of many academic bodies/societies. He has supervised four PhD candidates.

Abstract:

Metal oxide thin films have been used for a variety of applications, including photovoltaic devices, gas sensors, solar cells and so on. In comparison with the existing transparent conducting oxide (TCO) materials, indium oxide (In2O3) has been extensively studied because of its good optical transparency in the visible region, wide optical band gap and high electrical conductivity. Various techniques viz., sol-gel, pulsed laser deposition (PLD), molecular beam epitaxy (MBE), etc. has been used to deposit thin films of In2O3 in the literature. Chemical spray pyrolysis has been proved to be a significant and inexpensive technique wherein the properties of thin films can be engineered by altering the different process parameters associated with the spray equipment such as substrate temperature, substrate-nozzle distance, solution concentration, etc. It also offers advantages over other growth techniques such as low cost of the spray unit and raw materials and flexibility of doping elements into the parent system. In2O3 is a TCO material, possessing both direct and indirect optical band gap as well as a very low value of electrical resistivity. Among the various methods used to study the properties of indium oxide thin film, metal ion doping is one process wherein the properties of the film can be enhanced by the choice of a suitable dopant element. We present the influence of metal-ions (Sn and Li) doping on the structural, optical, electrical and formaldehyde sensing properties of sprayed In2O3 thin films. Finally, a comparison has been made between these two metal ion dopings.

Biography:

A. Sklyarova has completed her PhD from Lappeenranta University of Technology (Finland, 2015), now She is a postdoctoral researcher of Extreme Energy-Density Research Institute, Nagaoka University of Technology (Japan). Fields of interest: Superconductivity, Magnetism, Mössbauer spectroscopy, NMR, Iron-based and Copper-based superconductors, Inorganic material synthesis.

Abstract:

In this work the study of superconducting Sr-Ca-Cu-O layered system is presented. Study object is 02(n-1)n compound (critical temperature around 100-110 K) which shows some interesting properties like instability in moisturized air and possibility to entrance of water or carbon into the sample structure between layers [1-4]. Entrance of alien atoms into the structure may lead to the appearance of some interesting properties like asymmetry in hysteresis M vs. H curves due to the magnetic-field irreversibility [5]. The local properties study in both superconducting and block layers may help to clarify the question of air moisture influence on the hyperfine properties of these materials. Hyperfine properties study requires introducing into investigated samples some amount of substituent atoms which is used as a probe. There are several possibilities to add substituent elements inside Sr-Ca-Cu-O superconductor structure: substitution of a small amount of copper or calcium inside superconducting layers or substitution of a part of strontium atoms inside block layers. Here the effect of introducing of iron and europium into superconducting and block layers was studied. Systems with general formulas of Sr₂CaCu_1-xFe_xO_6±δ and Sr_2-xEu_xCaCu₂O_6±δ have been produced and investigated.

Biography:

Ranjan Chaudhury did his PhD from Tata Institute of Fundamental Research, Mumbai, India in1988. He did his Post-Doctoral work at ICTP (Trieste, Italy), McMaster University (Hamilton, Canada), University of Minnesota (Minneapolis, USA) and CNRS (Grenoble, France).  He is Professor (Associate) at SNBNCBS, Kolkata, India. He has published 40 papers in internationally reputed journals and in addition has 20 scientific publications of other types.  He has also been member of various scientific academies and societies such as American Chemical Society (USA) .

Abstract:

The family of cuprate superconductors synthesized over the last 25-30 years , has shown a remarkable promise in the journey towards fulfilling  our dream of achieving superconductivity at room temperature. The peculiarity and richness of microscopic physics  involved in superconducting pair formation  in cuprate systems, is discussed from theoretical perspectives with inclusion of our own work on this aspect.  The possible clues to achieving still higher superconducting transition temperature, obtainable from the studies of various classes of superconductors of both conventional and exotic types,  are sketched out.

Biography:

Gajanan Ramrao Mahajan was born on 16th Oct 1983 in Nanded, (M.S.), INDIA. He obtained his Bachelor of Science in 2003 and Master of Science (Physics) in 2006 from Swami Ramanand Teerth Marathwada University, Nanded. He got his Ph.D. degree in Physics in Jan 2012. Presently he is working as an Assistant Professor in Shri Datta Arts, Commerce and Science College, Hadgaon, Nanded (M.S.). His main research area of interests is in dielectric relaxation study of amides in non-polar solvents. He has 8 years teaching experience in Physics at graduate level.   

Abstract:

The dielectric relaxation studies of amides (Hexamethylphosphoramide, N-methylformamide, N, N-dimethylformamide and N-methylacetamide) have been carried out in non-polar solute (1, 4-dioxane) using time domain Reflectometry technique in the frequency range 10 MHz to 30 GHz. The hydrogen bonded model has been applied to understand the dielectric behavior of amides solution in terms of molecular interaction. Luzar proposed a more realistic hydrogen bonding model. The Kirkwood correlation factor, Bruggman factor, Excess dielectric properties were determined and discussed to yield the information on the molecular structure and dynamics of the mixtures.

Biography:

S N Pandey has completed his PhD from Avadh University. He is the Head of Department of Physics, Motilal Nehru National Institute of Technology, Allahabad, India. He has published more than 35 papers in reputed journals. He is recipient of UGC Research Award and many visiting fellowships. He is Life Member of many academic bodies/societies. He has supervised four PhD candidates.

Abstract:

The surface roughness and fractal analysis of virgin and swift heavy ions (SHI) irradiated BaF2 thin films were studied. Electron beam evaporation technique was used to deposit BaF2 thin films on Si <1 1 1> substrate at room temperature of thickness 100 nm. The films were irradiated with 120 MeV Ag9+ ions at various fluences in the range 1×1011 to 3×1013 ions/cm2. The virgin and irradiated films were characterized by atomic force microscopy (AFM). Fractal analysis on AFM images were performed using height-height correlation and autocorrelation functions to extract out roughness exponent, lateral correlation length and interface width. The computed results show that the surface roughness decreases with increase in ion fluence, while the fractal dimension increases initially followed by a decrease with ion fluence. The results show that the surface properties are greatly affected by the ion irradiation.

Biography:

DragoÅŸ Victor Anghel is a Senior Scientist (1st grade) at Horia Hulubei National Institute of Physics and Nuclear Engineering in Romania. His research interests are Theoretical condensed matter physics, Mesoscopic physics, Nanoscopic detectors and Complex systems

Abstract:

We revisit the Bardeen-Cooper-Schriefer (BCS) theory of superconductivity by studying the effect of the asymmetry of the attraction band with respect to the chemical potential, on the physical properties of the superconductor. The attraction band is defined as the interval in which the pairing interaction is manifested. Although in the standard BCS formalism —the center of the attraction band—is identified with the chemical potential, this represents only a convenient choice and not a physical constraint. Since the chemical potential and the attraction band may be influenced differently by the external conditions (e.g. pressure) or preparation methods (e.g. changing the mobility band by changing the chemical composition of the superconductor), it is natural to assume that is not identical to the chemical potential. Therefore, in our study we denote the chemical potential of the system by and we analyze the effect of the difference on the physical properties of the superconductor. We find that if the energy gap Δ and the temperature of the superconductornormal metal phase transition Tph change; the ratio Δ(T=0)/Tph changes also with (see Fig. 1). More dramatically, when μ≠μR, a population imbalance appears in equilibrium and the superconductor-normal metal phase transition becomes of the first order. If varies monotonically with pressure or doping, then a feature like the superconducting dome appears when the temperature of the phase transition is plotted vs. pressure or doping concentration.
 

Biography:

After post-graduate course (1969), I worked in the Department of the Theoretical and Mathematical Physics of S.I.Vavilov’s State Optical Institute, Leningrad, USSR; St.Petersburg State University, Physical Department; Institute of Military Medicine (St.Petersburg) and was invited to the Physical Department of University Federico II (Italy,Naples). I have published more than 160 scientific articles in physical, mathematical, biological and chemical journals. I have published four books (in Russian): “Bipolarons. Structure. Properties”(2011), “Modeling of the chemical compounds bioactivity”(2012), “Dynamics of the chemical elements in plants”(2012), “Theory of NMR chemical shifts 19F in aromatic chemical compounds”(2013). I am the со-author of the monograph “Nanotechnology. Fundamentals and Applications” Stadium Press LLC, USA(2013). I am Board Editor of 15 journals. I am member of “Academic Member of Athens Institute for Education and Research”. Repeatedly I have been included in the “Who's Who in the World”.

Abstract:

In the present paper, we propose an explanation of the ambiguity of the results of experiments on the study of high-temperature superconductivity of ammonia systems. At the heart of the theoretical interpretation of the experiments, we put the bipolaron model. In this study, we have shown mathematically that the barrier of repulsion between polarons can be effectively reduced if the polarons are in the macroscopic dielectric layers, or capillaries. We constructed the theory of polaron states in the macroscopic dielectric layers. We specify the conditions under which the polarons are hold in the layer between dielectrics. It was found that the electrostatic image forces lead to the appearance of additional forces of attraction between polarons. These forces are conditioned by oscillations of polarons around the position of their fixation. Derivations are given of the upper and lower limits on the width of the gap in which the polaron oscillations are not suppressed. In this case take place disappearance Coulomb repulsion of the polarons. A long-range resonant interaction of two oscillators resulting in the appearance of effective attraction between polarons is discussed. This leads to the formation of diamagnetic singlet bipolarons due to quantum exchange interactions and the effects of electron-electron correlations. For glass capillaries (quasi-one-dimensional bipolaron) and for gap between glass plates (quasi-two-dimensional bipolaron) we give quantitative estimates of the gap width and the critical temperature at which there is a barrier-free formation of the bipolaron in ammonia. Numerical estimates are obtained for a case of the bipolaron in ammonia. We obtained a quantitative evaluation, which indicate that the barrier-free formation of singlet bipolaron in ammonia begins at temperatures below 80K. How the experiment showed the electrical resistance of ammonia systems decreases abruptly by 10-12 orders of magnitude in this temperature range. At the same time, experiments have shown that for the bulk superconductivity superconducting phase is only ~ 0.01%.

Biography:

Avetik R. Harutyunyan is a Chief Scientist of Honda Research Institute USA Inc, USA. His international experience includes various programs, contributions and participation in different countries for diverse fields of study. His research interests reflect in his wide range of publications in various national and international journals. He is published one of article is Formation of Ripples in Graphene as a Result of Interfacial Instabilities. His Research interests are grapheme, scanning electron microscopy, ripple formation, solutal instability.

Abstract:

Growth of high qulity and large area graphene or control of its surface topography still remain challanging. The origin of surface ripples of graphene could be associated with the problem of thermodynamic stability of two dimensional membranes, presence of grain boundaries on the substrate, and the difference between the thermal expansion coefficients of graphene and a substrate. Recently the exploitation of graphene growth on liqufied substrate became one of the promising trends to address this challenge [1-3]. Our studies of graphene growth at elevated temperature by CVD method confirm not only the elimination of grain boundaries of Cu substrate due to liquefaction, but we have also observed new peculiar topographic patterns on the graphene surface in the form of wavy groves and single/double rolls, rough honeycomb cells, or combinations of both [4]. In-situ SEM studies on liquified Cu substrate suggest that these patterns originate from the dynamic instabilities caused by solutocapillary forces followed by non equilibrium solidification. In the course of graphene growth, these interfacial (Cu-C) instabilities govern the formation of ripples, developing a topographic pattern. These non-equilibrium processes can be well understood based on Mullins-Sekerka and Benard-Marangoni instabilities in diluted binary alloys. The model offers the control parameters over the grown graphene quality such as imposed carbon concentration gradient, thickness of the melted substrate, quenching rate, diffusivity and dynamic viscosity of carbon in the subtrate, and solutal surface tension of the carbon-liquid substrate system.

Biography:

Utpal Chatterjee has completed his PhD from University of Illinois at Chicago in 2007. Afterwards, he conducted his postdoctoral studies at Matreials Science Division of Argonne National Laboratory with Director’s fellowship. He joined University of Virginia in 2012. His reserach is focussed on experimental study of strongly correlated electronic systems. His principal expertise in Angle Resolved Photoemission Spectroscopy. His reserach over past 10 years has produced a number of high impact publications, which include Nat. Commun, 2015; 6: 6313 DOI: 10.1038/ncomms 7313, Nat. Phys. 10, 357; PNAS 110, 17774; PNAS 108, 9346; Nat. Phys. 6, 99; PRL 96, 107006.

Abstract:

Charge density waves (CDWs) and superconductivity are canonical examples of symmetry breaking in materials. Both are characterized by a complex order parameter – namely an amplitude and a phase. In the limit of weak coupling and in the absence of disorder, the formation of pairs (electron-electron for superconductivity, electron-hole for CDWs) and the establishment of macroscopic phase coherence both occur at the transition temperature Tc that marks the onset of long-range order. But, the situation may be drastically different at strong coupling or in the presence of disorder. We have performed extensive experimental investigations on pristine and intercalated samples of 2H-NbSe2, a transition metal dichalcogenide CDW material with strong electron-phonon coupling, using a combination of structural (X-ray), spectroscopic (photoemission and tunnelling) and transport probes. We find that Tc(δ) is suppressed as a function of the intercalationconcentration δ and eventually vanishes at a critical value of δ=δc leading to quantum phase transition (QPT). Our integrated approach provides clear signatures that the phase of the order parameter becomes incoherent at the quantum/ thermal phase transition, although the amplitude remains finite over an extensive region above Tc or beyond δc. This leads to the persistence of a gap in the electronic spectra in the absence of long-range order, a phenomenon strikingly similar to the so-called pseudogap in completely different systems such as high temperature superconductors, disordered superconducting thin films and cold atoms.

Biography:

Oleg Gradov is a Faculty of Institute for Energy Problems of Chemical Physics, RAS, Moscow, bld. His international experience includes various programs, contributions and participation in different countries for diverse fields of study. His research interests reflect in his wide range of publications in various national and international journals. He is published one of article is In Situ Tunable Laser Diode Spectroscopy OF The Processes And Products OF The Microwave-Induced Self-Organizatio In The Soft Mater Active Media. His Research interests are Photoinduced Self-Organization, Self-Oscillations, Self-Focusing, CAD, CAE, d'Arcy-Thompson, Artificial Cells, Morphogenesis, Abiogenesis.

Abstract:

We present here a novel measurement concept for the processes of self-organization in disperse semiconductor media under microwave irradiation [1] using in situ tunable diode laser spectroscopy (TDLS). Unlike the known laser diagnostics of the microwave plasma [2], our approach considers the study not of the discharge resulting from the magnetron flux / beam impact, but of the structures emerged in the disperse medium under the discharge and its torch products or directly under the magnetron effect. Self-assembly under the influence of the microwave field leads to the emergence of special properties of the structures formed in the microwave range, so one can speculate not only about self-assembled reaction-diffusion optoelectronics / photonics based on disperse semiconductors [3], but also about self-assembled reaction-diffusion microwave electronics and in the case of the magnetron-based experiments – even about self-assembled magnetooptics, microwave field-controlled magnetofluidics and self-assembled microwave spintronics. To date we do not possess a sufficient experience in autowave and self-oscillatory measurements (depending on either a gradient / increment of SWR / TWR (standing and travelling wave ratio, respectively) or the waves in the medium and their SWR / TWR, detected by the medium as a result of its self-organization under microwave radiation, is studied) [4]. If it is possible to perform a local laser irradiation in the variable spectral range, since it is also possible to characterize in situ the spectrum of the self-assembled structures and to suggest a possible mechanism of their self-assembly in the active medium from the known microwave sensitivity of the disperse semiconductor precursors. Tunable laser diodes and fiber spectrometers allow to perform such complex measurements successfully, and hence, stimulate the development of the novel research area in the framework of nonlinear physical chemistry, such as microwave-induced self-assembly of dissipative structures.

Biography:

Dr. Kun Yang is a Professor of Physics at Florida State University, and a world’s leader in theoretical condensed matter physics, especially well-known for his work on quantum Hall and other strongly correlated electronic systems. He has received numerous honors for his work, including Alfred Sloan Fellowship, Outstanding Young Researcher Award from Overseas Chinese Physics Association, and American Physical Society Fellowship. He currently holds a ChangJiang Chaired Visiting Professorship at Tsinghua University.

Abstract:

Topological states of matter support quasiparticle excitations with fractional charge and possibly exotic statistics of the non-Abelian type, known as non-Abelian anyons. They have potential applications for topological quantum computation. Most current experimental attempts to reveal such exotic statistics focus on interference involving edge transport. After a brief introduction of topological states (mostly in the context of fractional quantum Hall effect) in general, in this colloquium we will discuss how one can reveal the non-Abelian quasiparticle statistics using bulk probes. We show that bulk thermopower is a promising way to detect their non-Abelian nature, and measure the quantum dimension (a key parameter that quantifies non-Abelian statistics) of these anyons. This method is particularly effective in the Corbino geometry. We also demonstrate a novel cooling effect associated with them. We discuss application of these ideas to the specific candidate system of fractional quantum Hall liquid at filling factor 5/2, and topological insulator-superconductor hybrid systems. Some of the predicted behavior has been observed in recent experiments, which will also be discussed. This body of work has also motivated further theoretical efforts of using thermal probes to study non-Abelian anyons.

Biography:

Yang Xu has completed his B.S. from University of Science and Technology of China and now a PhD candidate in the Department of Physics and Astronomy, Purdue University.

Abstract:

Topological insulators (TI) are a novel class of quantum matter with a gapped insulating bulk yet gapless spin helical Dirac fermions. Recently [1], we have shown surface-dominated conductance in an intrinsic 3D TI, BiSbTeSe2 (BSTS), even close to room temperature for thin samples. In high magnetic field and low temperature, thin-flake samples exhibits well-developed quantum Hall effect (QHE), where the two parallel surfaces each contribute a half-integer e2/h quantized Hall resistance, accompanied by vanishing longitudinal resistance. Such “half-integer” QHE is a hallmark of massless Dirac fermions. Further [2], we performed local and non-local electrical and magnetotransport measurements in dual-gated BSTS thin film TI devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully-tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity of ~4e2/h at the double Dirac point, a series of ambipolar two-component “half-integer” Dirac quantum Hall states and an electron-hole total filling factor ν=0 state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction respectively. Such a system paves the way to explore rich physics ranging from topological magnetoelectric effects to exciton condensation.

Biography:

Serkan Caliskan received the B.S. degree in physics engineering and the PhD degree in physics from Gebze Technical University (Turkey) in 2003. He has worked as a postdoctoral researcher at Pohang University of Science and Technology (South Korea) and visiting assistant professor at Mississippi State University (MS,USA). He is currently a Professor of solid state physics at Fatih University, Istanbul. His research interests include quantum transport, electronic structure and nanoelectronic devices.

Abstract:

Spintronics is a developing an attractive field in both science and engineering due to possible new interesting applications. It plays an important role in nanotechnology and industrial applications. This field is related to role of spins or manipulating of spins through the nanostructures. Nanostructures (including nanotubes, nanowires, atomic wires), upon combining with spintronics, lead to new type devices with multifunctional and superior properties. Concerning the applications, detailed understanding of properties of these structures, interactions between electrons and the medium in which they move, therefore investigation of spin polarized transport (electron movement), evaluation of spin polarized quantities, examination of dependencies on other factors (topological disorder, electronic correlations, temperature, impurities, external field etc.) are required. In the present study, we perform density functional theory calculations on boron nitride nanotubes (BNNTs), which are containing substitutional transition metal (TM) dopants, to reveal the spin dependent electronic structure properties. The dopants are chosen as TM atoms to be able to induce possible spin dependent behavior and/or to emerge the spin polarization in the structures. Both optimized pure and doped several zigzag nanotubes with infinite lengths are investigated. We mainly concentrate on electronic structure and magnetic properties in terms of chiral vector describing the doped zigzag nanotubes. Hence we extract the impact of chirality and dopants on the spin dependent energy gap and other relevant quantities for relaxed nanotubes. BNNTs and carbon nanotubes are compared, and obtained results are discussed for the possible applications of these nanotubes, as fundamental structures, in the field of spintronics.

Biography:

Gwiy-Sang Chung rhas compledted his Ph.D degree from Toyohashi University of Technology, Toyohashi, Japan, in 1992. He joined the ETR), Daejon, South Korea, in 1992, where he worked on Si-on-insulator materials and devices. Moreover, he also worked as a visiting scholar at UC Berkeley and Stanford University, CA, USA, in 2004 and 2009, respectively. He is now a professor in the School of Electrical Engineering, University of Ulsan, Ulsan, South Korea. His research interests include Si, SiC, ZnO, AlN-M/NEMS, flexible self-powered wireless sensors nodes, energy harvesting, localized surface plasmon resonance (LSPR), and graphene/MoS2-based composites. He is the author or co-author of more than 145 scientific and technical SCI international journal papers

Abstract:

In this work, piezoelectric and plasmonic effects on a flexible acetylene (C2H2) sensor based on silver (Ag) nanoparticles (NPs) decorated zinc-oxide (ZnO) nanorods (NRs) were realized. Using visible light illumination, the sensing properties can be modulated and the power consumption can be reduced significantly. Upon exposure to 1000 ppm C2H2 under 8.36 mWcm-2 light illumination, the power consumption of the sensor noticeably reduced from 3.48 W (in dark) to 1.64 W. A large number of light induced chemisorbed oxygen ions were generated in the Ag-coated ZnO NRs forest due to the strong coupling effect between the surface plasmon Ag NPs and the ZnO NRs. This resulted in increased surface charge densities, which facilitated the sensor to react with the C2H2 molecules at lower operating temperature, and hence reduce the power requirement. Moreover, the sensor exhibited reliable detection of C2H2 gas within the concentration of 3-1000 ppm including a maximum sensor response of 26.16, response-recovery time of 66/68 sec, excellent mechanical stability of a bending angle up to 90o, and 104 cycles of repeated deformation processes. These results might facilitate research in developing a low power C2H2 sensor and will open up new approaches for future light modulated gas sensors.

Biography:

Prof. Jhinhwan Lee received his Ph.D. degree at the Seoul National University in 2002 and has been postdoctoral associate in Cornell University until 2009. He is currently a faculty member in KAIST physics department and the director of Quantum Tunneling Metrology Center associated with KRISS. He has published multiple papers on nanotubes and high-Tc superconductors in reputed journals.

Abstract:

The role of magnetism, antiferromagnetic spin fluctuations, or phonons on superconductivity in iron-based superconductors have been a long debated issue. With a recent discovery of high Tc near 100 K on monolayer FeSe on a perovskite substrate, understanding the possible roles of enhancing the Fe-based superconductivity by the supporting layers in contact with the Fe-pnictide or Fe-chalcogenide layers is getting an ever-increased attention. Using a homemade variable temperature-magnetic field spin-polarized STM, we have performed spectroscopic-imaging STM measurement on the parent-state superconductor Sr4V2O6Fe2As2 with each unit cell layer composed of superconducting FeAs layer sandwiched by two Sr2VO3 layers. The hybridization between the localized V electrons and the itinerant Fe electrons causes electron transfer to the FeAs bands and generates a Gamma-centered electron pocket leading to a relatively high critical temperature near 30 K, as well as a ubiquitous Fano resonance with a signature of Fano lattice made of V d electrons. In the QPI measurement, we observed the kinks and the partial replicas of the QPI dispersion due to bipartite bosonic modes with characteristic mode energies near 14 meV and 20 meV, whose characteristics agree excellently with the two distinct electron-boson coupling-induced self-energies in Migdal’s approximation. By a comparative study with spin-polarized and normal STM tips, we also observed atomic scale magnetic memory effect of the V atoms controlled with low energy spin-polarized tunneling current and used it to reveal underlying magnetic domains in the FeAs layer and their dynamics. The magnetic and nematic phase transitions near 50 K and 150 K respectively revealed by this technique favorably agrees with the phase transitions detected by bulk and transport measurements. The variable temperature-magnetic field spin-polarized STM offers a novel atomic-scale insight to the roles of the spin, charge, lattice and orbital degrees of freedom in unconventional superconductors and emergent quantum materials.

Biography:

Stuart Tessmer completed his PhD in 1995 at the University of Illinois at Urbana-Champaign (UIUC); he studied as a postdoc at the Massachusetts Institute of Technology (MIT) from 1995-1998. At Michigan State University he specializes in experimental condensed matter physics and is currently the Physics Department Associate Chair & Undergraduate Program Director.

Abstract:

In this talk I will present scanning tunneling microscopy data of a Bi₂Se₃ crystal with superconducting PbBi islands deposited on the surface. Local density of states measurements show induced superconductivity in the topological surface state with a coherence length of order 540 nm. At energies above the gap the density of states exhibits oscillations due to scattering caused by a nonuniform order parameter. Strikingly, spectra taken on the superconductor side of the  interface show Dirac-cone-like behavior suggesting an inverse proximity effect – that is topogical states induced onto the superconductor.

Biography:

Louis H Kauffman received  a B.S. in Mathematics from MIT in 1966 and a PhD in Mathematics from Princeton University in 1972. He has taught at the University of Illinois at Chicago since 1971 and has been a Full Professor since 1984. He is the Editor in Chief of the Journal of Knot Theory and Its Ramifications and the editor of the World Scientific Book Series on Knots and Everything. He is a Fellow of the American Mathematical Society since 2014. He is past president of the American Society for Cybernetics and the recipeint of the Warren McCullocy Award (1993) and the Norbert Wiener Gold Medal (2014) of that Society. He is the 2015 recipient of the Bertalanffy Medal for Significant Contributions to Complexity Thinking. Kauffman is the author of numerous books on knots and their applications. His resarch is primarily focused on the structure and discovery of topological invariants of knots and links.

Abstract:

Majorana fermions are Fermionic particles that are their own anti-particles. Mathematically, a standard fermion such as an electron can be seen as a composite of two Majorana fermions. At the level of operators in quantum field theory this is seen by writing F = a + ib where F is the fermion annihilation operator and a and b are elements of a Clifford algebra where a^2 = b^2 = 1 and ab = -ba. Then F* = a - ib and we have FF = F*F* = 0 and FF* + F*F is a scalar, the usual fermion relations. Remarkably, rows of electrons in nanowires have been shown to have correlation behaviors that corresponds to this decomposition, and topologically remarkable is the fact that the underlying Majorana fermions have a natural braiding structure. This talk will discuss the braiding structure of Majorana fermions and possible applications to topological quantum computing

Biography:

Junji Haruyama graduated from Waseda University, Tokyo, Japan in 1985. Right after that, he joined Quantum device laboratory, NEC Corporation, Japan and worked until 1994. He received PhD in Physics from Waseda University in 1996. During 1995–1997, he worked with the University of Toronto, Canada (Prof. J Xu Lab), and also Ontario Laser and Lightwave Research Center, Canada as a Visiting Scientist. Since 1997, he has worked at the present Aoyama Gakuin University as a Professor until now. He was also a Visiting Professor at NTT Basic Research Laboratories (Dr. Takayanagi’s Nano-science Lab), Institute for Solid State Physics (Prof. Iye’s Nano-science Lab), The University of Tokyo, and Zero-emission Energy Center, Kyoto University, Japan. He has been a Principal Researcher at Air-Force Office of Scientific Research, USA since 2010. He has peer review publications of over 100 and 4 patents, and has also done more than 150 invited talks. He has been Co-author of over 30 books, a Referee of over 50 journals and a Member of international committees (organizer, adviser and chairman) of over 30 conferences.

Abstract:

Two-dimensional (2D) atom-thin layers have attracted significant attention after the discovery of primitive fabrication method of graphene, mechanical exfoliation of graphite using scotch tapes. As a van-der Waals engineering, various atom- thin layers and those hybridization have been recently realized. In the talk, first, I will present magnetism and spintronics arising from edges of 2D atom-thin layers, graphene, few-layer black phosphorus (BP) and hexagonal boron-nitride (hBN). I created nanomesh (NM) structures, consisting of honeycomb like array of hexagonal pores, with specified pore-edge atomic structure (i.e., zigzag type) on individual layers. Interestingly, hydrogen-terminated graphene NM (H-GNM) shows flat-band ferromagnetism, while it disappears in oxygen-terminated GNM. On the other hand, O-BPNM exhibits large ferromagnetism due to ferromagnetic spin coupling of edge O-P bonds, whereas it is eliminated in H-BPNM. O-hBNNM also shows large ferromagnetism due to edge O-B and O-N bonds, while it disappears in H-hBNNM. These are also highly sensitive to annealing temperatures to form zigzag pore edge. These open a considerable avenue for realizing 2D atom-thin flexible magnetic and spintronic devices, fabricated without using rare-earth magnetic atoms. Second, I will show creation of the world-thinnest Schottky junction on few-layer molybdenum disulfide (MoS2), one of the transition metal dichalcogenides. The 2H-phase of MoS2 has direct band gaps of 1.5−1.8 eV. It is demonstrated that electron-beam (EB) irradiation to the 2H-phase causes semiconductor- metal transition to 1T-phase and atomically-thin Schottky junction with barrier height of 0.13−0.18 eV is created at the interface of 2H/1T regions. These findings also indicate a possibility that the effective barrier height is highly sensitive to electrostatic charge doping and almost free from Fermi-level pinning when assuming predominance of the thermionic current contribution. This EB top-down patterning opens the possibility to fabricate in-plane lateral heterostructure FETs,which have shown promising scaling prospects in the nanometer range, and/or local interconnects directly with metallic phase (1T) between (2H)MoS2 transistors, resulting in ultimate flexible and wearable in-plane integration circuits without using 3D metal wirings. Finally, I will also briefly talk about introduction of spin-orbit interaction into graphene by light hydrogenation(<0.1%).

Biography:

Igor Tralle is a physics professor at the Faculty of Mathematics and Natural Sciences, University of Rzeszów. His research interests are concentrated around Solid State and Semiconductor Physics, charge carrier transport in low-dimensional and quantum structures, linear and nonlinear Optics, quantum cascade lasers as well as Mathematical Physics. During the last couple of years his research interests are moving also towards THz detection and generation and metamaterials. He is an author or co-author of about 100 research papers published in high-rank peer reviewed scientific journals. Close

Abstract:

The field of research termed as Quantum Information Theory and more specifically, Quantum Computation  attracts nowadays a great deal of attention. Recently Di Vincenco [1] proposed what was called Di Vincenzo's check list, the list of requirements  the quantum system has to fit in, for one has the possibility to implement on such a basis the quantum computer, the Holy Grail of those who deal with quantum information and quantum computation. These requirements are: (i) well defined qubits; (ii) relatively long decoherence times (iii) initial state preparation and some others equally important.  The aim of our work is to advance new approach to producing the qubits  in electron ballistic transport in low-dimensional structures such as double quantum wells or double quantum wires (DQW). The  qubit would arise as  a result of quantum entanglement of two specific states of electrons in DQW-structure. These two specific states are the symmetric and anti-symmetric (with respect to inversion symmetry, or mirror image) states arising due to tunneling across the structure, while entanglement could be produced and controlled by means of the source of  non-classical light. Thus, in such structure one can get the two-particle pure states entanglement: in our case two subsystems are the electron (subsystem A ) which can be either in the state  or in the state and the photons (subsystem B). The state is the product state if there exist  such that, otherwise the state is called entangled . The product states are: where  is associated with symmetric electron state and  with the EM-field state characterized by the number of photons n and , where  is associated with anti-symmetric one and  with the EM-field state characterized by the number of photons n-1, whereas  entangled states   in our case are : We examined the possibility to produce quantum entanglement in the framework of Jaynes-Cummings model and have shown that the entanglement can be achieved due to striking and unusual phenomena related to Jaynes-Cummings model, namely series of ‘revivals’ and ‘collapses’ in the interaction of a quantized single-mode EM-field with a two-level system.

Biography:

Gayan Prasad Hettiarachchi completed his PhD in Physics at Osaka University in 2015. He is currently working as a specially-appointed assistant professor at the Insititute for NanoScience Design at Osaka University. He is interested in experimentally investigating strongly-correlated electron systems in order to elucidate vital correlation effects and the underlying mechanisms that ultimately lead to interesting physical properties and phase transitions.

Abstract:

Insulator-to-metal transitions (IMTs) still remain a central theme in condensed-matter physics despite many zealous experimental and theoretical efforts. The persistence of this question for decades can be attributed to the complexities that arise due to strong correlation-effects and many degrees of freedom that exist in real systems. The seminal work of Mott introduced insulating character originating from strong on-site Coloumb repulsion energy U. The ratio of U and Hubbard bandwidth W (U/W) is a critical parameter that tips the balance of insulating and metallic states. However, in real systems, correlation effects are not limited to these two parameters, and effects from intra-atomic exchange energy, orbital degeneracy, crystal-field splitting, etc., come into the equation. For electrons in a deformable lattice, electron-phonon interaction energy S and the induced deformations become crucial parameters that govern the evolution of the trasfer integral t. Aluminosilicate zeolites (M_aAl_aSi_bO_2(a+b)) provide an ideal, but non-trivial playground for exploring such interactions. The negative charge of Al_aSi_bO_2(a+b) framework is balanced by the cations M_a and present a deformable lattice. Guest electrons can be introduced into this deformable lattice through encapsulation of guest atoms. Experimental investigations show that even with same/comparable effective U, subltle changes in the deformable lattice (in turn change in the deformation potential), and tuning of S by changing M can give rise to different ground states. The competition between U, t, and S together with the electron density govern the balance between insulating vs. metallic states and magnetic vs. nonmagentic states directing the dscussions of IMTs towards a relatively old but less discussed branch, the “polaron physics”.

Biography:

Haifeng Song has completed his PhD from Tsinghua University. He is Director of research group in the fields of condensed mater physics and material physics. His research interests include the equation of state, phase transition, transport properties of metals, etc. He has published more than 40 papers in reputed journals and has been serving as an Editorial Board Member of repute.

Abstract:

The thermodynamic stable phase of cerium metal in the high pressure regime has been studied by combining density functional theory with the Gutzwiller variational approach (LDA+Gutzwiller), which can include the strong correlation effect among the 4f electrons in cerium metal properly. Our numerical results show that the α″ phase, which has the distorted body-centered-tetragonal structure, is the thermodynamic stable phase in the intermediate pressure regime (5.0-13.0 GPa) and all the other phases including the α′phase (α-U structure), α phase (fcc structure) and bct phases are either metastable or unstable. Our results are quite consistent with the most recent experimental data. We also studied the α-γ iso-structure transition in cerium, we found that the first order transition between α and γ phases persists to the zero temperature with negative pressure. By further providing a newly finite temperature generalization of the LDA+G method (using the mean-field potential approach), the entropy contributed by both electronic quasiparticles and lattice vibration included, we obtain the Gibbs free energy at a given volume and temperature, from which we get the α-γ transition at finite temperature and pressure. Our results indicate that the electronic entropy and lattice vibrational entropy both play important roles in the α-γ transition. We also calculated the equation of state and phase diagram of cerium, finding good agreement with the experiments.

Biography:

S C Wang has completed his PhD from Tsinghua University. He is a Research Fellow in the fields of Condensed Mater Physics and Material Physics. His research interest includes the equation of state, phase transition and transport properties of metals. He has published about 10 papers in reputed journals.

Abstract:

Increasing demands to subsequent design and engineering of new high performance materials are boosting the precise knowledge of melting and transport properties of metals. Here we report an ab initio molecular dynamics study of melting and diffusion coefficients of aluminium under high pressure. The melting curve up to 400 GPa is predicted from the twophase method, which has a good agreement with experiments and other calculations. The diffusion coefficients up to 140 GPa and 10000 K are obtained from the mean square displacements and the autocorrelation functions of atomic velocities via the Green-Kubo relation, which reveal that the original entropy-scaling law is violable, but an exponential relationship still exists between the dimensionless diffusion coefficients and the pair correlation entropy.

Biography:

Hongzhou Song has obtained a Doctor of Philosophy Degree (PhD) in Theoretical Physics from China Academy of Engineer Physics. He is Associate Research Fellow of Institute of Applied Physics and Computational Mathematics.

Abstract:

Actinide compounds have been attracting scientific attentions because of their industrial, military, and environmental importances, as well as the vast theoretical prospects around the intriguing 5f electrons. In comparison with lots of studies extensively on actinide oxides aiming to reveal their ground-state properties as well as the electronic behaviors under pressure, the hydrides of actinide elements receive much less concerns. This is probably because that actinide oxides are always very stable at ordinary conditions, while actinide hydrides are easily oxidized within the earth’s atmosphere. However, hydrides
are also very important to the atmospheric corrosion of actinide metals. Recently, several researches turn their interests into electronic structures and physical properties of hydrides such as PuHx and UH3. The electronic structure and properties of α and β uranium hydride and deuteride under extreme conditions are investigated within the DFT and DFT+U formalisms. It is found that both αand β-UH3 are ferromagnetic in their ground states.Applying stretching strains does not change the groundstate magnetic ordering and the atomic magnetization around each uranium atoms. In contrast,compression strains will enhance the covalency character of the U-H bonds and transform UH3 into nonmagnetic states. The underlying electronic reasons are carefully analyzed through Bader charge calculations and electronic wavefunction analysis. Our obtained physical results accord well with previous studies, and serve as a reference for understanding the electronic behaviors of other actinide
materials under compression.

Biography:

Nathan Newman is a Professor of Solid State Sciences and is a faculty member in the Materials Program at Arizona State University. His research interests focus on the investigation of novel solid-state materials for microwave, photonic and high-speed applications. His current work involves synthesis, characterization and modeling of novel superconductor junctions and materials, III-N semiconductors, low loss dielectrics for microwave communication, and novel photovoltaic material. He is an author and co-author of over 200 technical papers, has 12 patents, has an h-index over 40 and his papers have been cited over 5,000 times. He has received the IEEE Van Duzer Award, is a Fellow of the IEEE and the American Physical Society, and has won Faculty Teaching Awards at Northwestern University and Arizona State University. He also serves as an Associate Editor for Materials in the IEEE Transactions of Applied Superconductivity and has served as the Chair of the US Committee on Superconductor Electronics and ASU’s LeRoy Eyring Center for Solid State Sciences.

Abstract:

Despite the practical importance of achieving a small loss tangent (tan δ) and near-zero temperature coefficient of resonant frequency (τF) for microwave communication systems, a fundamental understanding of which mechanism determine these important parameters had not been firmly established. In this talk, I will focus on my group’s work using modern experimental and theoretical condensed matter methods to identify the responsible mechanisms. We will focus our discussions on results from Ni-doped BaZn‑Ta2/3O3 (BZT), since it is the highest performer at room temperature. We will also show that the conclusions are general for other commonly-used materials. Ba(Zn1/3Ta2/3)O3 exhibits the unusual combination of a large dielectric constant, εr, and a small loss tangent at microwave frequencies. Using ab-initio electronic structure calculations, we show that d-electron bonding in BZT and related materials is responsible for producing a more rigid lattice with higher melting points, enhanced phonon energies than comparable ionic materials and thus inherently less microwave loss. The properties of commercial materials are optimized by adding dopants or alloying agents, such as Ni or Co to adjust the temperature coefficient, tF to zero. This occurs as a result of the temperature dependence of ε offsetting the thermal expansion. At low temperatures, we show that the dominant loss mechanism in these commercial materials comes from spin excitations of unpaired transition-metal d electrons in isolated atoms (light doping) or exchange coupled clusters (moderate to high doping), a mechanism differing from the usual suspects. At high temperatures, we give evidence that loss also arises and may be dominated by localized hopping transport. The temperature coefficient of resonant frequency (τf) of a microwave resonator is determined by three materials parameters according to the following equation: τf = - (½τε+½τμ+αL), where αL, τε and τμ are defined as the linear temperature coefficients of the lattice constant, dielectric constant, and magnetic permeability, respectively. We have experimentally determined each of these parameters for undoped and Ni-doped Ba(Zn1/3Ta2/3)O3 materials. These results, in combination with density functional theory (DFT) calculations, have allowed us to develop a nearly complete understanding of the fundamental mechanisms responsible for τf.

Biography:

Kirstin Alberi received a B.S. in Materials Science and Engineering from the Massachusetts Institute of Technology in 2003 and a PhD in Materials Science and Engineering from the University of California, Berkeley in 2008. She is currently a Senior Staff Scientist at the National Renewable Energy Laboratory, where she conducts basic research on the epitaxy of novel semiconductors and heterostructures and studies the optical and electronic properties of semiconductor alloys for photovoltaic and solid-state lighting applications. She also serves as a member of the Editorial Board of Journal of Physics D: Applied Physics.

Abstract:

Isoelectronic impurities whose electronegativity and size are very different than the host atom the substitute can introduce resonant states in either the conduction or valence band that induce substantial changes in the electronic bandstructure.  Nitrogen is well known to create a resonant state above the conduction band minimum that causes band mixing and a 180 meV/% N drop in the bandgap energy. Bismuth also produces a similar effect in the valence band of GaAs that leads to a bandgap reduction of 88 meV/% Bi.  This strong dependence of the bandgap energy on the alloy composition makes both GaAs_1-xN_x and GaAs_1-xBi_x alloys potentially important materials for high efficiency multijunction solar cells, infrared lasers, LEDs and detectors.  Moreover, they provide rich systems for exploring the interaction of localized states dispersed throughout a host matrix. Statistically occurring N pairs and clusters strongly localize electrons in the bandgap, while analogous Bi-related states localize holes.  These states can then be made to interact by increasing their concentration.  For example, wavefunction overlap between localized N pair states creates delocalized superclusters that further perturb the host GaAs electronic structure.  Application of a magnetic field can then be used to reduce the Bohr radius of excitons bound at these states, fragmenting the superclusters.  The investigation of such phenomena provide insight into the evolution of localized impurity states into delocalized alloy states and shed light on the birth of  novel semiconductor alloys.

Biography:

Yuko Ichiyanagi has completed her PhD from Yokohama National University, Japan. She is an Associate Professor of Yokoham National University since 2009. She has published more than 30 papers in reputed journals and has been serving as an international advisory committee member of some reputed conferences.

Abstract:

Magnetic nanoparticles (MNPs) encapsulated with amorphous SiO2 ranging several nm were prepared by our original wet chemical method. Local structure of magnetic cluster was analyzed by X-ray absorption fine structure (XAFS). MNPs prepared by this method, Si ions are located on the surface, and this characteristic structure enables amino-silane coupling and functionalization is made easier. We have established the way of functionalization of these magnetic nanoparticles in order to conjugate other molecules. We have confirmed that our particles were introduced into the living cells, and these particles were localized by the external magnetic field. Then cancer cell selective NPs were further developed by attaching folic acid. Mn-Zn ferrite nanoparticles were prepared and optimized in composition and particle size. To estimate heating effect of magnetic nanoparticles for an application of hyperthermia treatment, ac magnetic susceptibilities were measured and analyzed. Samples were examined for heating agent from the result of frequency dependence and particle size dependence of imaginary part of ac
magnetic susceptibilities χ”. A temperature increase of approximately 18 K was observed in a 192-Oe, 15-kHz field for Mn-Zn ferrite NPs. Increase rate of temperature was found to be high enough to suppress cancer cells. In vitro experiment showed an extensive hyperthermia effect. In addition, we have suggested out NPs as an agent of MR imaging, CT imaging, magnetic particle imaging (MPI) and mass spectrometric imaging for diagnostics. Our magnetic nanoparticles are expected to develop theranostics system.

Biography:

Elie A Moujaes completed his PhD in theoretical condensed matter physics at the age of 28 from the University of ottingham, UK (2007). He has two postdoctoral xperiences: One at the University of ottingham and the other at the Federal University of Minas Gerais (UFMG). He has more than 10 publications in well respected journals and is currently an adjoint professor at the Federal University of Rôndonia. His research involves magnetism and magnetic materials as well as DFT calculations associated with electron phonon coupling for various bi-dimensional exotic materials.

Abstract:

The Fe and Ni sublattice magnetizations of ultrathin iron-nickel alloy nanonjunctions [Fe1-cNic] between Fe and Co leads are inspected. For c ≤ 0.4, the alloy has a bcc structure and becomes fcc otherwise. A combined EFT and MFT treatment is used to obtain the sublattice magnetizations of Fe and Ni in the individual layers as a function of temperature and concentration. This is achieved by calculating single site spin correlations within EFT and making use of reliable experimental data such as lattice parameters a, stiffness spin constants D, and Curie temperatures Tc leading to reasonable values of the exchange parameters J. According to our model, the alloys forming the bcc nanojunctions we examine (c = 0.0841; 0.204; 0.268) are ferrimagnetic with the absence of a compensation temperature while those for the fcc structures (c = 0.5; 0.81) are ferromagnetic. These EFT results feed the MFT calculations for the nanojunction from the interface inwards. The effect of adding several alloy layers to both bcc and fcc types is also considered. The sublattice magnetizations are necessary elementsfor certain spin dynamic computations, such as ballistic magnon transport across embedded nanojunctions in magnonics.

Biography:

Jan Smotlacha has completed his Ph.D at the age of 33 years from Czech Technical University. Now he works as the senior research scientist in the Bogoliubov Laboratory of Theoretical Physics in the Joint Institute for Nuclear Research in Dubna. He has published about 13 papers in reputed jounals or conference proceedings.

Abstract:

The graphene nanostructures are the materials derived from the hexagonal carbon lattice. In our research of the graphene nanoparticles we are concerned with two kinds of them: the graphene wormhole and the graphitic nanocone. Due to extremely curved geometry of the graphene wormhole, the relativistic effects could be observed here: the mass of the electrons appearing close to the wormhole center can be much higher than the invariant mass. This fact together with the effect of the spin-orbit interaction can cause the appearance of the chiral massive fermions. The calculations show that on the wormhole bridge the density of the corresponding zero states should be very high, so it could be used to detect the wormhole centers during the production. The geometric structure we acquire by the connection of 2 graphene sheets with the help of 12 heptagonal defects. In addition to the theoretical calculations, we carried out the numerical simulations. The graphitic nanocone is the structure which arises by the addition of one or more pentagonal defects into the original graphene structure. In the numerical simulations, the calculations of the electronic structure are based on the exact atomic structure, in the continuum approximation we work with different approximations: either we suppose the pure conical geometry or we simulate the smooth geometry close to the tip by different supplementary effects like the placement of the charge into the place of the tip. Next significant effect influencing the electronic structure of the nanocone is the spin-orbit interaction.

Biography:

Mukhtar Ahmad is a assosate professor in university of Cosmsats, Pakistan. He is published so many papers.He is research interestes are M-type hexagonal ferritesGd-substitutionSEM analysisDC resistivityM–H loops.

Abstract:

Li-ferrites are scientifically advanced smart materials and their structural and magnetic properties can be modified for a particular application by controlling the synthesis conditions and better choice of metal ions. In the present work, single phase samples of lithium zinc ferrites with general formula LiCo_0.5-xZn_xFe₂O₄ (where 0≤x≤0.5) were synthesized by sol gel auto combustion method. To study the mass loss (%) and endothermic and exothermic reactions as a function of temperature, thermal analyses (TGA/DTA) were carried out for a selected sample. The structure and morphology for all the samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns confirm that all the samples retain phase purity of spinel structure when substituted with Zn contents in place of Co ions. However, the structural parameters such as lattice constant, cell volume and X-ray density were altered after Zn-substitution into the spinel lattice. The SEM images show that the grain size estimated by line intercept method was found to be unchanged by substituting Zn ions because the values of ionic radii of Zn and Co are almost equal. The M-H loops for all the samples show a low value of coercivity (a few hundred oersteds) which confirms the soft magnetic nature of these ferrites. Moreover, the values of saturation magnetization and remenance are in good agreement with earlier reported values for this structure. The observed parameters suggest that these ferrites may be potential candidates for a cathode material in Li-ion batteries, core materials and microwave devices.

Biography:

M Kofoworola Awodele received MSc in Physics from University of Ibadan, Nigeria in 2002 and a PhD in Physics from Loughborough University, Loughborough UK in 2015. She is working at Ladoke Akintola University of Technology, Ogbomoso. Her research interest is theoretically investigating novel mechanism for electron and spin transport in nanostructures looking at electron transport in semiconductor superlattices.

Abstract:

The electron transport in semiconductor superlattices exhibits interesting phenomena, which are quite different from those that occurred in a bulk material. This depends on the electronic band structures in the semiconductor superlattices. The energy band gaps of the superlattices are aligned, but the magnitudes of the band gaps are different. The difference in the width of the energy gap in different semiconductors forms the boundary of the conductivity band for perfect semiconductor superlattices that is modulated periodically and leads to the formation of energy minibands.

Biography:

Matteo Tonezzer received his PhD degree “cum laude” in Physics at the University of Trento (Italy) in 2011. He won the Young Scientist Award from the European Materials Research Society (EMRS) and worked in research centers in France (ESRF), Brazil (UFMG), Vietnam (HUST), Italy (INFM) and USA (GeorgiaTech). He currently works for IMEM in the Italian National Research Council, authored more than twenty papers on international journals, is reviewer for 25 international peer-review journals, editor of international peer-review journals, organizer and chairman of international conferences. His main area of interest concerns the sensing properties of nanostructured organic and inorganic materials.

Abstract:

Nanostructured metal oxides are nowadays attracting more and more interest in several fields due to their unique properties. Binary n-type semiconducting oxides (SnO2 and ZnO principally) are known as excellent gas-sensing materials, whereas p-type oxides (mainly NiO) are only recently being investigated, because they are more difficult to grow in a controlled way. In this presentation we show both n- and p-type metal oxide nanowires grown by different methods, studying their sensing properties in multi- and single-nanowire devices. Single SnO2 nanowires are grown by CVD and used to experimentally study the depletion layer modulation model that is at the basis of such sensing devices. The mechanism is confirmed, with a depletion layer experimental value of 14 nm. Furthermore, stable and very fast (few seconds) response and recovery are found, proving that these sensors are good for real-time applications. NiO polycrystalline nanowires grown via a simple hydrothermal method are used as sensors with tuneable selectivity in different practical applications related to clean energy: their response to different gases can be enhanced in order to optimize their use with different steam reforming fuel cells, and demonstrating that post-processing of the nanosensors outputs can be a valuable tool to overcome metal oxide weaknesses. At the end of this contribution we will show how metal oxide micro- and nanostructures can be functionalized with organic molecules to greatly decrease the working temperature of hybrid sensors close to room temperature. The metal oxide – organics interface seems to be crucial to achieve the best performance.

Biography:

Anshul Kumar Sharma received his M.Sc. degree in Physics from Department of Physics, Himachal Pradesh University Shimla, India in the year 2009 and he did M.Phil. degree in Physics in the year 2011 from Department of Physics, Guru Nanak Dev University, Amritsar, India. Presently, he is working towards his Ph.D. degree in the same department. His research interests are preparation and characterization of carbon nanotubes based functional hybrid materials and their application as gas sensors.

Abstract:

Carbon nanotubes (CNTs) possessing unique structure and properties are attractive building blocks for novel materials and devices of important practical interest. Particularly, Multi wall carbon nanotubes (MWCNTs) have attracted extensive attention in sensing application owing to their unique one-dimensional carbon nanostructure and electrical properties. However, the insolubility or poor dispersibility of pristine CNTs in common solvents poses a serious obstacle to their further development. Various attempts have been made to obtain homogeneous CNT dispersions in both aqueous and organic media. Among those approaches, chemical modification of side walls, defect sites, and open ends are often found to result in changes of the structural, mechanical, and electronic properties of CNTs. Generally, carbon nanotubes are very sensitive to many types of target molecules showing an apparent lack of selectivity. This drawback of carbon nanotube sensors can be overcome through functionalization of nanotube surface in order to provide molecular specificity or unbalanced promoted sensitivity to a class of chemical species. Introduction of functional groups, such as carboxyl and amino groups, not only can improve CNTs solubility in various solvents, but also are useful for the further chemical link with other compounds. Recently, in order to improve the sensing performance of these MWCNTs based sensors, many sensing materials such as conducting polymers  metals and metal oxides  have been anchored on the surface of MWCNTs and play important roles in the improvement of the sensitivity and selectivity of the resultant gas sensors.  Phthalocyanine (Pc), as an excellent sensing material, has been extensively studied based on its high sensitivities, excellent thermal and chemical stability. Substituting functional groups on phthalocyanine molecules make them soluble in various organic solvents and thus enable them for low cost solution processing techniques such as spin coating and self-assembly etc Therefore, we expect that combining the nanoscale CNTs with gas sensing active Pc would feature not only the intrinsic properties of CNTs and Pc arising from the mutual interaction between CNTs and Pc but also enhance the gas sensing behaviour of CNTs. In this work, we have prepared a hybrid material of MWCNTs-COOH and Hexa-fluorinated copper phthalocyanine (F₁₆CuPc). The formation of F₁₆CuPc/MWCNTs-COOH hybrid was confirmed by UV-Visible, Raman and FT-IR spectroscopy.  SEM, TEM and AFM studies revealed that F16CuPc₈ molecules were successfully anchored on the surface of MWCNTs-COOH through π-π stacking interaction. Subsequently, a chemi-resistive sensor have been fabricated by drop casting F₁₆CuPc/MWCNTs-COOH hybrid onto alumina substrate. The gas sensing potential of the fabricated hybrid materials has been tested upon exposure to different hazardous gases like NO₂, NO, Cl₂ and NH₃ at different operating temperatures. It has been demonstrated that F₁₆CuPc/MWCNTs-COOH hybrid is highly selective towards Cl₂ with minimum detection limit of 100 ppb. The response of sensor increases linearly with increase in Cl₂ concentration. The results obtained emphasize on the application of F₁₆CuPc/MWCNTs-COOH hybrid material in Cl₂ sensing applications.

Biography:

Himanshu Verma has done Masters in Physics from Michigan Technological University, Houghton, MI in 2006 and Ph.D. in Applied Physics from University of South Florida, Tampa, FL in 2015. Dr. Verma served as Assistant Professor of Physics in Southern Chicago with a community college for 1 year and about to begin investigation on Novel Magnetic Materials as Research Associate at Morgan State University in Baltimore, Maryland.

Abstract:

The understanding of physical motions such as rolling, sliding, stick-slip, and spinning is of great importance, since the energy loss and wear between the contacting surfaces is determined by the mode of motion of these particles. When a lateral force is applied onto a nano size particle lying on a surface, what happens to its translational motion? Does it roll, does it slide, or both? How can the force required be predicted from the particle’s properties? These questions have relevance in technological applications where nano size particles are used in lubricating mixtures and in nano-electromechanical devices, where they are used as building blocks. Using Lateral Force Microscopy to provide the forces required to produce translational motion of nano-sized particles across a planar substrate will help understand the tribological properties that inform their use in such applications. Such knowledge will help in designing new lubricants, hard disk storage technology, new materials for post chemical mechanical polishing (CMP), and generally in the reliable, repeatable and controllable manipulation of nano-size particles on substrates. We have utilized Atomic Force Microscopy and Force Spectroscopy to study the tribological properties of nanoscale polymeric particles to explore how the friction between these nanoscale spherical objects translating over planar substrates is related to interfacial energy and the mechanical properties for these particles. A technique for modifying the mechanical properties was developed and used to provide a set of samples over which we had control of the elastic modulus without corresponding changes in the chemical bonds. Lateral force microscopy was used to measure the force required to translate asymmetric, nanoscale particles of controlled size, surface chemistry and moduli. The effects of work of elastic modulus of polystyrene microspheres, contact radius between particle and substrate have been studied for the different modes of particle translation under an external force.

Biography:

T V Torchynska is Professor of Physics at National Polytechnic Institute of Mexico. She obtained MS (1973) in Solid State Physics at National Technical University of Ukraine, PhD (1978) and Habilitation (1991) degrees in Physics and Mathematics at Institute of Semiconductor Physics at National Academy of Sciences of Ukraine. She is the author of over 350 articles published in prestige journals, the monographs “Mechanisms of Degradation of III-V Semiconductor Light-Emitting Diodes and Lasers”, “Harwood Academic Publisher”, 1997, and “Nanocrystals and Quantum Dots of Group IV Semiconductors” American Scientific Publisher, 2010, 18 book chapters and 14 patents.

Abstract:

ZnO has attracted scientific attention during the last decade owing to its potential application in short-wavelength and hightemperature optoelectronics, such as short-wavelength light emitting diodes, photodetectors, ultraviolet lasers, etc. To fabricate the optoelectronics devices n- and p-type ZnO NC layers are required. As in any II-VI semiconductors, the preparation of p-type ZnO NC layers is the difficult task owing to the high concentration of native shallow donors. It was shown recently that Ag is a most promising element from the group IB atoms for p-type ZnO doping. Additionally, Ag-doping stimulates the near band edge (NBE) emission in ZnO NCs that is interesting for optoelectronics. The emission, structure and the aging process have been studied in the silver doped ZnO nanorods (NRs) obtained by ultrasound spray pyrolysis with different Ag concentrations within of 1-4 at%. Electronic scanning microscopy (SEM), X ray diffraction (XRD), photoluminescence (PL)
spectroscopy and its temperature dependences have been applied. It is revealed that at low Ag content (1-2 at%), the doping improves essentially the structure and emission of ZnO Ag NRs. Simultaneously, the inter-planar distances in ZnO NR crystal lattice decreases and the new Ag related PL band with the peak at 2.87-2.95 eV at 10 K appears in PL spectra. At higher Ag content (3-4%) the PL intensity of majority PL bands falls down together with the stimulation of orange PL band intensity, the inter-planar distances in ZnO NR crystal lattice increase and the formation of metallic Ag nanocrystals have been detected by
XRD. The aging process is accompanied by the new Pl band (2.87-2.95 eV) falls down as well and intensity raising the orange PL band. The PL temperature dependence study permits to analyze the nature of defects responsible for the new Ag-related PL band (2.87-2.95 eV) and for the orange PL band. The optimized concentrations for the Ag doping of ZnO NRs have been revealed.

Biography:

Dr. L. N. Singh has completed Ph. D. in Experimental Solid State Physics in 1992 at IIT, Bombay. He is the Head, Department of Physics, Dr. B. A. Technological University, Maharashtra, India. He was also worked as Dean, Faculty of Science, Gombe State University and Head, Department of Physics, Gombe State University. He has 20 years of teaching and research experience. He has published more than 20 papers in reputed journals presented more than 50 papers in conference/seminar. He supervised 5 PhD students successfully till this date.

Abstract:

Transport behavior and magnetoresistance in solgel prepared Nd_0.7Sr_0.3-xBa_xMnO₃ (0≤x≤0.3) nanomanganite system have been investigated in temperature range 10 -330 K. The composition and structural properties were studied at various concentrations by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). X-ray diffraction (XRD) pattern confirms the single phase nature of the samples with orthorhombic crystal symmetry. The average A-site ionic radii which is directly related to tolerance factor and size variance, plays a vital role in magnetotransport properties. The metal-insulator transition temperature, T_MI, shifts toward low temperature with increasing Ba substitution from 205 to 95 K and shows semiconducting like behavior at low temperature. It is shown that the correlated polaron model accounts for the temperature dependence resistivity and magnetoresistance in the entire temperature range. The number of charge carriers, n decreases as Ba²⁺ ion concentration increases. The small polaron binding energy, e_p, is found to decrease as Ba²⁺ ion concentration increases. The increase in the thermally assisted activation energy, U₀, is observed as the system varies from Sr- to Ba- substitution. The number of charge carriers, n, is decreases as Sr²⁺ ion concentration decreases which is responsible for the increase in resistivity values.

Biography:

Dr. L. N. Singh has completed Ph. D. in Experimental Solid State Physics in 1992 at IIT, Bombay. He is the Head, Department of Physics, Dr. B. A. Technological University, Maharashtra, India. He was also worked as Dean, Faculty of Science, Gombe State University and Head, Department of Physics, Gombe State University. He has 20 years of teaching and research experience. He has published more than 20 papers in reputed journals presented more than 50 papers in conference/seminar. He supervised 5 PhD students successfully till this date.

Abstract:

Transport behavior and magnetoresistance in solgel prepared Nd_0.7Sr_0.3-xBa_xMnO₃ (0≤x≤0.3) nanomanganite system have been investigated in temperature range 10 -330 K. The composition and structural properties were studied at various concentrations by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). X-ray diffraction (XRD) pattern confirms the single phase nature of the samples with orthorhombic crystal symmetry. The average A-site ionic radii which is directly related to tolerance factor and size variance, plays a vital role in magnetotransport properties. The metal-insulator transition temperature, T_MI, shifts toward low temperature with increasing Ba substitution from 205 to 95 K and shows semiconducting like behavior at low temperature. It is shown that the correlated polaron model accounts for the temperature dependence resistivity and magnetoresistance in the entire temperature range. The number of charge carriers, n decreases as Ba²⁺ ion concentration increases. The small polaron binding energy, e_p, is found to decrease as Ba²⁺ ion concentration increases. The increase in the thermally assisted activation energy, U₀, is observed as the system varies from Sr- to Ba- substitution. The number of charge carriers, n, is decreases as Sr²⁺ ion concentration decreases which is responsible for the increase in resistivity values.

Biography:

Elie A Moujaes completed his PhD in theoretical condensed matter physics at the age of 28 from the University of ottingham, , UK (2007). He has two postdoctoral xperiences: One at the University of ottingham and the other at the Federal University of Minas Gerais (UFMG). He has more than 10 publications in well respected journals and is currently an adjoint professor at the Federal University of Rôndonia. His research involves magnetism and magnetic materials as well as DFT calculations associated with electron phonon coupling for various bi-dimensional exotic materials.

Abstract:

The Ising effective field theory (EFT) method has proved to be a successful tool providing the appropriate exchange constants of basic ferromagnetic materials. In this work, Fe and Ni sublattice magnetizations of n-layered ultrathin iron-nickel alloy nanonjunctions [Fe1-cNic]n between Fe and Co leads, c being the Ni concentration inside the alloy, are inspected using a combination of EFT and mean field theory (MFT). Our EFT+MFT cocktail is believed to provide a simple yet accurate picture about the magnetizations, in complex ferromagnetic systems, through the calculation of parameters without the need to complicated theoretical models and in the absence of DFT results. For c < 0.4, the alloy has a bcc structure and becomes fcc otherwise. In the former case, the n layers of the alloy are connected to bcc Fe leads, whereas in the latter case, fcc Co leads are used instead. The exchange constants J and sublattice magnetizations σ calculated through EFT alone, are considered basic ingredients for quantum transport properties across the nanojunctions; total magnetizations within each layer are also exploited. Such EFT-based results then feed MFT calculations for the nanojunction from the interface inwards. Interestingly, it was observed that for bcc nanojunctions, the shape of all magnetization curves is unique for all c and for any value of n. This completely changes for fcc nanojunctions where differences are spotted for various concentrations. Special attention is given to the invar (c=0.5) and permalloy (c=0.81) alloys where some kind of saturation occurs when layers n ≥2 are constructed.

Biography:

C S Ting is a professor of physics at the University of Houston. His major research area has been on theoretical condensed matter physics including transport theories in various solid state systems, superconductivity in copper oxide materials and iron pnictides, magnetism, metal-insulator transition, electronic property of graphene, solids with the spin-orbit couplings, and strongly correlated electron systems. He is the principal investigator in theory at the Texas Center for Superconductivity at the University of Houston, and a fellow of APS in the Division Condensed Matter Physics. 

Abstract:

Fully- and semi-hydrogenated graphene, named graphane (C₆H₆)^1,2 and graphone (C₆H₃)^3,4, were previously found to be nomagnetic semiconductor with a direct gap of 3.5 eV and antiferromagnetic semiconductor with an indirect gap of 2.46 eV, respectively. Here, by means of first-principles calculations, we predict another kinds of partially hydrogenated graphene systems⁵: C₆H₁ and C₆H₅, which are ferromagnetic (FM) semimetal and FM narrow-gaped semiconductor with an indirect gap of 0.7 eV respectively. When properly doped, the Fermi surface of the two systems consists of an electron pocket or six hole patches in the first Brillouin zone with completely spin-polarized charge carries. If superconductivity exists in these systems, the stable pairing-symmetries are shown to be p + ip for electron doped case, and anisotropic p + ip for hole doped case. The predicted systems may provide fascinating platforms for studying the novel properties of ferromagnetism and triplet-pairing superconductivity.  In addition, the electronic structures of hydrogenated graphene C₆H₂ and C₆H₄  have  also been studied. We find that C₆H₂ is a Dirac semimetal with 2 highly anisotropic cones located well inside the first Brillouin zone,  and C₆H₄ is a semiconductor with a gap of ~3.35 eV. A detailed discussion of their properties will be presented.

Biography:

Rita John is Professor and Head, Department of Theoretical Physics, University of Madras, Chennai, India. She is Fulbright Visiting Professor at the Department of Physics and Astronomy, Texas Christian University, Fort Worth, Texas, USA (2014). She has been teaching solid state physics for graduate students over 18 years. The book, ‘Solid State Physics’ authored by her and published by Tata McGraw Hill publisher (2014) is used globally by graduate students. She guides Ph.D., M.Phil., M.Sc., and M.Tech. projects. She has over 50 international publications. She is the recipient of various awards and prizes for her academic and research contributions.

Abstract:

Silicene, germanene, and tin; the 2D analogues of graphene are structurally different from graphene due to the buckling distorsions in the lattice. Hybridization in graphene is purely sp². It is sp²/sp³ mixed orbitals in other 2D structures that results in buckling and causes pronouced effects in their properties. Structural, electronic, optical and mechanical properties are investigated. Density Functional Theory with Generalized Gradient Approximation as implemented in CASTEP is used. At the Dirac point, the dispersion curve is linear in graphene and quadratic in all other materials. Critical points, saddle points, Van Hove singularities are investigated in band structures and density of states histograms. Optical properties unveil the frequency dependence and non linear response of absorption. Graphene exhibits  prominent aborption in the ultraviolet region and shifts towards the infrared region in all other 2D structures.  Intensity of absorption increases in layered structures. Birefringence is exhibited by single and layered structures. Real part of refractive index establishes the anisotropic behaviour. Bilayer exhibits semimetallic behaviour. Trilayer portrays metallic nature. Study on mechanical properties brings out the unique stiffness of graphene. Bonding characteristics and  charge density contours endorse that covalency reduces from graphene to stanene, due to which elastic moduli decreases from graphene to stanene. Poisson’s ratio shows increased brittleness in graphene, semimetallic nature in silicene and germanene, and metallic nature in stanene. Although silicene, germanene, and stanene posses only 20%, 14%, and 9%  of Young’s modulus, the bonding nature facilitates its suitability in semiconductor industry along with substrates to enhance the conduction mechanism.

Biography:

P M Trivedi is presently working as an Associate professor at Bhavan’s Sheth R. A. College of science, affiliated to Gujarat University, a UGC India recognised university. He completed his Ph.D. in2004 from Bhavnagar University. He has assisted some government educational institutes for syllabus designing as wel as laboratory establishments for under graduates and research purpose. Though he is mainly involved in UG nd PG teaching, he has played key role in cultural activities of the college and done career counselling for a large number of students.

Abstract:

A magnetic liquid also called Ferro Fluid[1], is a colloidal dispersion of surfactant coated ferrite particles of nano-size. The behavior of such fluid is of super-paramagnetic nature[2]. In such diluted continnum micron size graphite particles were dispersed. This created magnetic holes [3]. As their size varies, their coagulations in the form of particle chains under external magnetic field is also affected. Light transmitted through thin films of such materials exhibit birefringence. Experimentally observed extinction parameters are reported to have reversal effects [4-5].  Role of gradient density distribution of anisotropic magnetic particles is discussed for the observed phenomenon. Necessary theoretical model is developed and compared with the experimental data.

Biography:

Anamika Vitthal Kadam has completed her PhD at the age of 31 years from Bharti Vidyapeeth University, Pune, MH, India. She is working as Assistant Prof in D.Y. Patil Engg and Tech, Kolhapur, MH, India and having guideship of D.Y. Patil University. Se has published more than 25 papers in national and international journals and achieved a project under young scientist scheme with one minor research project.

Abstract:

The electrochromic properties of organo-inorganic hybrids of WO3/PPy thin films have been synthesized with a two step processes successfully. The WO3 layer was prepared by electrodeposition technique on conducting glass substrate (Indium doped Tin Oxide-ITO) followed by thermal treatment and polypyrrole thin films were deposited using chemical bath deposition (CBD) technique. The structural, morphological, optical and electrochromic responses of WO3, PPy and WO3/PPy films are described. To study the electrochromic (EC) properties of the as deposited films, cyclic voltammogram (CV), chronoamperometry (CA), hronocoulometry (CC) and optical modulation were performed. The kinetic investigation (response time) and coloration efficiency were found to be enhanced appreciably. The WO3/PPy shows improved EC performance than their solitary act.

Biography:

Nan Xu has completed his PhD in 2013 from Institute of Physics, Chinese Academy of Sciences. Afterwards, he conducted his postdoctoral studies at Swiss Light Source, Paul Scherrer Insitut in 2013-2015, and at Ecole Polytechnique Federale de Lausanne (EPFL) from 2015 to now. His academic insterests are using angle-resolved photoemission spectroscopy to study the strongely correlated systems and novel quantum states. He has published more than 30 papers in reputed journals over past 5 years, and been invited speaker in more than 10 international conferences.   

Abstract:

Recently, significant advances in topological theory extend the topological classifications from non-interacting insulators to strongly correlated insulators, and further to semimetals. In this talk, I will report our recent works about direct visualizations of topological quantum states with angle-resolved photoemission spectroscopy (ARPES), including:

• The observation of energy-band dispersions [1-2] and spin texture [3] of the metallic surface states on SmB₆ as compelling evidences for the predicted strongly correlated topological kondo insulator states.
• Experimental realization of Weyl semimetal states in TaAs by direct observation pairs of 3D Weyl cones in the bulk states [4], matching remarkably well with our first-principles calculations.
• Experimentally realization of ideal Weyl semimetal state in TaP, where only single type of Weyl fermions contributing the exotic transport properties [5].
• Discovery first type-II Weyl semimetal state in MoTe₂ in wihch Fermi surfaces consist of a pair of electron- and hole- pockets touching at the Weyl node and Weyl fermions strongly violate Lorentz invariance [6].
• Preliminary results on new topological quantum states.

Biography:

Pavel Belov received his PhD from the University of Hamburg in 2010. He is a teaching assistant at the Department of Physics of the St.Petersburg State University. He has published more than 20 papers in the reputed journals and conference proceedings.        

Abstract:

Excitons states and exciton light-coupling in bulk semiconductors and heterostructures have been under intensive study in the last few decades. Although the exciton binding energy is relatively small in the bulk semiconductors, typically lower than the lattice vibration energy at room temperature, in the semiconductor heterostructures it can increase significantly, up to several times. The radiative properties of an exciton are characterized by the radiative decay rate, which is defined by the exciton-light coupling. In our study, the binding energy and the corresponding wave function of excitons in GaAs-based finite square quantum wells (QWs) are calculated by the numerical solution of the three-dimensional Schroedinger equation. The precise results for the lowest exciton state are obtained by the Hamiltonian discretization using the high-order finite-difference scheme. The calculations are compared with the results obtained by the standard variational approach. The exciton binding energies found by two methods coincide within 0.1 meV for the wide range of QW widths. The radiative decay rate is calculated for QWs of various widths using the exciton wave functions obtained by direct and variational methods. The radiative decay rates are confronted with the experimental data measured for high-quality GaAs/AlGaAs and InGaAs/GaAs QW heterostructures grown by molecular beam epitaxy. The measurements and results of calculations are in good agreement.

Biography:

Claire Levaillant graduated with a Ph.D. from California Institute of Technology in 2008. She has since then occupied visiting positions at Harish Chandra Research Institute in India and at the University of California at Santa Barbara in the USA. While in Santa Barbara she worked with the Microsoft Research Station Q team. She has authored papers in the fields of group theory and quantum computation.

Abstract:

Exotic particles named Fibonacci anyons have drawn increasing interest for topological quantum computation. Their specificity is the density of the braid group representations (Freedman-Larsen-Wang, 2001), that is any quantum gate can be approximated by braiding of the anyons, up to some arbitrary precision. In this talk, we show how adding measurement operations allow making some exact quantum gates probabilistically. From these probabilistic quantum gates, we derive exact ancillas, which we use in turn to make exact key quantum gates. Many recent theoretical studies have shown evidence for the existence of these exotic particles and have exhibited experimental platforms for their use. The field is vibrant on-going theoretical and experimental research in condensed matter physics.

Biography:

Qili Zhang has completed his PhD China Academy of Engineering Physics. He is a Research Fellow in the fields of Condensed Mater Physics and Computational Physics. His research interests include the equation of state, phase transition and transport properties of materials. He has published about 10 papers in reputed journals.

Abstract:

The T=300 K isotherm of diamond is calculated by using density-functional molecular dynamics. The results show that the PAW-PBE potential is more close to the experimental data. The thermodynamic states accessible under shock conditions are given by the principal Hugoniot which satisfying the Rankine-Hugoniot equations, the internal energy and pressure at a given density and temperature are calculated by using density-functional molecular dynamics, the initial state was taken to be un-shocked diamond with ρ₀=3.475 g/cm³, T=300 K, and P₀≈0GPa, which obtained from the T=300 K isotherm. Our principal Hugoniot is similar with the result of Nichols in the literature, but is little higher in pressure and temperature, the solid-liquid coexistence region is from ρ=6.0 g/cm³ to 6.95 g/cm³. Knowledge of the sound velocity is essential for a variety of research areas; moreover, the pressure and temperature dependence of the sound velocity can be used to constrain the equation of state. This work presents two theory methods to calculate the sound velocity of solid phase along the principal Hugoniot: One by using the Gruneisen equation state and the isotherm at T=300 K, the other by using the specific heat, the pressure derivative with respect to the density and to the temperature along the principle Hugoniot, the results are consistent with each other. The optical reflectivity of the diamond on the principal Hugoniot is also calculated, the result is consistent with the experimental results in the literature.

Biography:

Claire Levaillant graduated with a Ph.D. from California Institute of Technology in 2008. She has since then occupied visiting positions at Harish Chandra Research Institute in India and at the University of California at Santa Barbara in the USA. While in Santa Barbara she worked with the Microsoft Research Station Q team. She has authored papers in the fields of group theory and quantum computation.

Abstract:

Exotic particles named Fibonacci anyons have drawn increasing interest for topological quantum computation. Their specificity is the density of the braid group representations (Freedman-Larsen-Wang, 2001), that is any quantum gate can be approximated by braiding of the anyons, up to some arbitrary precision. In this talk, we show how adding measurement operations allow making some exact quantum gates probabilistically. From these probabilistic quantum gates, we derive exact ancillas, which we use in turn to make exact key quantum gates. Many recent theoretical studies have shown evidence for the existence of these exotic particles and have exhibited experimental platforms for their use. The field is vibrant on-going theoretical and experimental research in condensed matter physics.

Biography:

Prof. Rao had a brilliant academic record at Andhra University where he got the B.Sc (Honors), M.Sc and D.Sc degrees and also taught for two years. He spent two years each at Duke and Harvard Universities as postdoctoral fellow. He has been teaching at the University of Massachusetts, Boston since 1968 where he is currently Distinguished Professor in the Physics Department. He was elected a Fellow of the American Physical Society, Division of Laser Science in 2010 "in recognition of a long record of significant contributions to the nonlinear optics of organic materials and their applications to optical power limiting, Fourier phase contrast microscopy and medical image processing". He published over 120 papers in peer reviewed prestigious journals like Physical Review Letters, Applied Physics Letters, Optics Letters etc. covering research areas- nonlinear optics, magnetic resonance, microwave absorption, optical Fourier techniques for breast cancer diagnostics, phase contrast and multimodal optical microscopy etc. He holds ten patents and one of these on Fourier Phase Contrast microscopy is recently licensed to industry for marketing the technology.

Abstract:

We have been working on basic nonlinear optics of the protein complex Bacteriorhodopsin (bR) thin polymer films with milliwatt cw lasers. The unique feature of this material is its flexibility. Absorption of a visible photon by bR triggers the photo cycle, starting from the initial B state to the relatively long lived M state via short lived intermediate states. It can revert to the initial B state thermally in milliseconds via short lived intermediate states or can go back directly to B state within nanoseconds by shining blue light. Both life times can be altered by orders of magnitude using chemical methods or genetic mutation. The process of switching between B and M states (chemical isomers) can go in both directions depending on wavelength, intensity and polarization of the incident light offering a variety of possibilities for manipulating amplitude, phase and polarization. Over the years we studied the basic nonlinear optics- four wave mixing, phase conjugation, photo induced anisotrpy etc. We successfully exploited the unique properties for many applications- all optical switching, modulation, computing, information processing, power limiting for laser eye protection, medical image processing, transient Fourier holography etc. More recently we are focusing on optical Fourier techniques for early detection of micro calcifications in mammograms for breast cancer diagnostics. We also developed an innovative technique of Fourier phase contrast microscopy and multimodal optical microscopy for live cell imaging of biological samples. I will present some highlights of our work with particular reference to development of inexpensive biomedical devices.

Biography:

Sadik Guner received the B.S.degree in physics education from Middle East Technical University(METU), the M.S.degree in physics from FatihUniversity,and the Ph.D.degree in physics from GebzeTechnical University, Kocaeli,Turkey, in 1994, 1999, and 2003, respectively.He is currently a Professor of solid state physics at Fatih University,İstanbul. His research interests include magnetic materials, thermoelectric generators and thin films.

Abstract:

The pure ZnO and Cr doped ZnO (Cr:ZnO) thin films (thickness: 200 nm) were grown on both side polished silica (SiO₂) substrates by RF magnetron sputtering at room temperature. As deposited samples were annealed at 400 °C, 500°C and 600 °C for 45 min in quartz annealing furnace system, respectively. The structural and chemical composition analyses were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectrometry (EDS). XRD studies revealed that the almost single crystalline hexagonal Wurtzite structure of pure ZnO film disappears with increasing Cr concentration and annealing process contributes the long range crystal order of films. SEM images show that average grain size is around 30 nm. EDS results indicate that only Zn, Cr and O elements are present in the Cr:ZnO thin films. The electrical properties were investigated by using the Four Point Probe (FPP) method. The smallest electrical resistivity for doped samples were obtained at 600 °C  annealing temperature and specifically as 5.34×10⁻⁴ Ω⋅cm belonging to Cr_8.21ZnO. The electrical conductivity and carrier concentration of the films are increased while mobility carriers are decreased with increasing Cr content. The optical properties were studied in the wavelength region of 200-1000 nm by employing UV-vis spectroscopy. Pure ZnO and Cr:ZnO films that include 3.22 at. % Cr content (or less), have transmittance above 70 % between 400-1000 nm before annealing.  It was observed that all annealed samples have higher average transmittance in the range of 200–1000 nm as compared to as-deposited films. Tauc plots were drawn to specify the optical energy band gap (E_g) of  as-deposited and annealed samples. The E_g increases from 3.24 eV to 3.90 eV with incrasing Cr concent from x: 0 at. % to 3.22 at. % and then decreases to 1.60 eV for 11.80 % Cr concentration.

Biography:

Roberto Zivieri is a theoretical condensed matter physicist. He got the Master Degree in Medicine and Surgery and the Master Degree in Physics with honors and the PhD in Physics (grade excellent) from the University of Modena, Italy. He is author of about 200 scientific contributions including 70 articles in international and reputed journals. He has been serving as an editorial board of repute. He is member by invitation of the American Physical Society, of the American Chemical Society and of the Italian Society of Mathematical Physics. He is winner of the APS Award “Outstanding Referees 2016”.

Abstract:

In recent years the study of low-dimensional magnetic systems has become topical for its several technological applications but also for a complete understanding of the underlying physics of magnetic nanostructures. Very recently, for their challenging features, great attention has been given to the investigation of the static and dynamical properties of magnetic nanostructures with special regard to magnonic crystals, a class of periodic magnetic systems characterized by modulated properties. As shown by several theoretical approaches, the ferromagnetic materials composing periodic magnetic systems can be described as metamaterials since they exhibit effective properties. For instance, it is possible to define an effective magnetization and an effective permeability both in a lossless and in a lossy ferromagnetic medium, an effective wavelength and an effective wave vector for collective excitations and, under some conditions, an effective diamagnetic behavior of ferromagnetic periodic systems. Moreover, the band structure of different kinds of magnonic crystals can be determined. The  aim of this talk is to give an overview of the recent results obtained on the study of metamaterial and effective properties of two-dimensional ferromagnetic nanostructures. Micromagnetic simulations and simple analytical calculations first applied to thin ferromagnetic films and then to differen kinds of two-dimensional periodic magnetic systems allow to extract the above described metamaterial properties. Some possible applications based on the effective properties for tailoring new magnetic devices are suggested.

Biography:

Rikio Konno has completed his PhD at the age of 28 years from University of Tokyo and postdoctoral studies from Tsukuba University. He is the Science Section Head of Kindai University Technical College, a famous college based on Kindai University in Japan. He has published more than 25 papers in reputed journals.

Abstract:

We investigated the temperature dependence of thermal expansion of heavy fermion systems based on the Coqblin-Schrieffer model (the Kondo lattice model) theoretically. Thermal expansion of heavy ferimon systems has been unresolved based on the microscopic model. In order to study thermal expansion, we use Takahashi’s method that is based on the Landau expansion of the free energy about the small volume. Takahashi’s method was applied to the free energy derived by Hanzawa and Ohara based on the Coqblin-Schrieffer model. We found that thermal expansion at low temperatures showed an exponential behavior. Near the Kondo temperature, thermal expansion showed T-linear dependence. We also discussed thermal expansion of the localized paramagnon that was valid in one of heavy fermion compounds.

Biography:

PaweÅ‚ ZiÄ™ba is an Assistant Professor in University of Rzeszow, Poland. He has completed MSc in Physics, Pedagogical University in Rzeszów and PhD in Physics from University of Rzeszów. His research interests are methods for terahertz radiation generation, analysis and design of met materials, optical processing of information and holography.

Abstract:

All the proposed designs of metamaterials are characterized by ever-increasing sophistication of fabrication methods. We propose a comparatively simple recipe for the fabrication of a metamaterial, which is both gyrotropic and of the simultaneously negative permittivity and permeability. The idea is to make a mixture of three ingredients, where one of them would be responsible for the negativity of μ, while the other two would be responsible for the negativity of ε. The first component of the mixture is the “swarm” of single-domain ferromagnetic nanoparticles, immersed in a mixture of other two, silver and mercury cadmium telluride (MCT). The choice of silver is determined by the fact, that as it was shown, the permittivity of a mixture of silver and a dielectric material can be negative in some frequency domain. In addition, silver is that it is a diamagnetic material. It means that considering the “swarm” of single – domain ferromagnetic nanoparticles suspended in a mixture containing silver, we can neglect the interaction between their magnetic moments and treat the whole mixture as superparamagnetic. The choice of MCT is determined by the remarkable dependence of its energy gap on the fraction of cadmium in the compound. In its turn, it leads to the strong dependence of the electron concentration on this fraction as well as on the temperature. It enables to adjust each of the two frequency domains, where ε <0 and μ <0 and makes them simultaneously negative. Similar dependence on the electron concentration exhibits Pb1-xSnxTe. By carrying out the computer simulations, the domains where metamaterial to exist, relative to all parameters characterizing the model, that is, the temperature, external magnetic field, parameters of nanoparticles, and the fraction of cadmium in MCT as well as the fraction of tin in Pb1-xSnxTe and relative concentrations of the mixture components are established.

Biography:

Majid Niaz Akhtar completed his PhD studies in the field of nanotechnology from Universiti Teknologi PETRONAS (UTP), Malaysia. He has expertise in the field of electromagnetics, material science (Adanced magnetic materials) and RF microwave devices (EM Antenna, Nanodevices). He completed his Masters of Philosophy and Masters of Science in (Applied Physics specialization with industrial Electronics) from Bahauddin Zakariya University, Multan, Pakistan. He has got gold medal awards in his M.Phil and Masters from Bahauddin Zakariya University, Multan. On completion of his Masters studies he has worked as a lecturer in Army Public Degree College, Multan. During his M.Phil studies, he worked as visiting lecturer in Govt. College of Technology, Multan and Bahauddin Zakariya University (BZU), Multan. Working at Bahauddin Zakariya University, he has been involved in conducting basic research in the fields of advanced material science for micrwave absorption and memory storage devices. Currently, he is working in Comsats institute of Technology (CIIT), Lahore as Assistant Professor in Department of Physics.

Abstract:

The influence of Cu-Zn substitution on the structural and morphological characteristics of Ni nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for  Cu-Zn substituted Ni nanoferrites. The nanocrystalline ferrites of Cu-Zn with different compositions were synthesized using sol gel self combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to find out the properties of CuZn substituted nanocrystalline ferrites. Single phase structure of CuZn substituted in Ni nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to be increased by increasing Cu contents in spinel structure.  The better morphology with well organized nanocrystals of CuZn ferrites at x=0 and 1.0 were observed from both FESEM and TEM analysis. The average grain size was 35-46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded hysterises MH loops. The magnetic saturation and remanence were increased as Cu contents increased. However, coercivity follow the Stoner-Wolforth model except for x=0.6 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirms the superparamgentic behaviour of the CuZn substituted in Ni nanocrystalline ferrites. Furthermore, CuZn substituted Ni nanocrystalline ferrites may be suitable for many industrial and domestic applications such as component of transformers, core, switching, and MLCI's due to variety of the soft magnetic characteristics.

Biography:

Muhammad Maqbool works as an Associate Professor of Physics at Ball State University. He has obtained his Ph.D. degree in experimental condensed matter physics from Ohio University, USA, in 2005. He has obtained his Master of Science degree in Medical & Radiation Physics from the University of Birmingham, UK, in 1998. His area of research is experimental condensed matter and surface physics. He has published over 60 research papers and book chapters in peer reviewed journals. Dr. Maqbool has presented his work in several international meetings, conferences and workshops. He has also worked as an organizing chair of the American Physical Society Ohio Region Fall-2011 meeting. Dr. Maqbool has obtained over half a million dollars in grant from various organizations like National Science Foundation, Indiana Academy of Science and Ball State University.

Abstract:

Microlaser plays an important role in laser technology and applications due to its smaller size. When a lasing material is deposited around an optical fiber, the cylindrical shape of the fiber acts as cavity for laser production. Transition metals and rare-earth elements are good candidates to produce such kind of laser due to their characteristic light emission in all UV, visible and IR regions of the spectrum. In this talk, an infrared laser made out of titanium doped aluminum nitride (AlN:Ti) deposited around an optical fiber will be discussed. Optical fibers of 12 μm diameter were coated with a sputter-deposited layer (4 μm thick) of titanium (1 at: %)-doped amorphous aluminum nitride. When optically pumped by an Nd:YAG green laser at 532 nm, laser action was observed in whispering gallery modes around the fiber (in a ring shape) at 780:5 nm with a quality factor Q > 1500. Other modes were also observed between 775 and 800 nm. The primary and secondary modes give a mode separation of 4:6 nm. No waveguide modes were observed in the cavity