Day 3 :
- Superconductivity and Superfluidity | Organic Electronics| Theoretical and Experimental study of Soft Matter
Chair
Ranjan Chaudhury
S N Bose National Center For Basic Sciences, India
Co-Chair
Myung Joon Han
KAIST Institute for interdisciplinary research, Korea
Session Introduction
Michael W Roth
Northern Kentucky University, USA
Title: The rich landscape of organic molecules on graphitic surfaces: what molecular dynamics shows
Time : 09:30-09:50
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.
Myung Joon Han
of KAIST Institute for interdisciplinary research, Korea
Title: Reduced dimensionality and emerging material property in perovskite oxide superlattices: A first-principles study
Time : 09:50-10:10
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.
Leonardo dos Santos Lima
Federal Center for Technological Education of Minas Gerais, Brazil
Title: Spin superfluidity in the frustrated two-dimensional anisotropic XY model
Time : 10:10-10:30
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).
Oomman K Varghese
University of Houston, USA
Title: Functional oxide nanoarchitectures for emerging energy and clinical technologies
Time : 10:50-11:10
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.
S N Pandey
Motilal Nehru National Institute of Technology, India
Title: Effect of metal-ions (Sn and Li) doping on the structural, optical and gas sensing properties of In2O3 nanocrystalline thin films
Time : 11:10-11:30
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.
A Sklyarova
Nagaoka University of Technology, Japan
Title: Local properties study of substituted Sr-Ca-Cu-O superconducting structur
Time : 11:30-11:50
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 Sr2CaCu1-xFexO6±δ and Sr2-xEuxCaCu2O6±δ have been produced and investigated.
Ranjan Chaudhury
S.N. Bose National Center For Basic Sciences, India
Title: Microscopic understanding of high temperature superconductivity and its possible role towards enhancement of critical temperature
Time : 11:50-12:10
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.
Gajanan Ramrao Mahajan
Commerce and Science College, India
Title: Dielectric Relaxation Study and molecular interaction of amides in 1, 4-dioxane by Using Time Domain Reflectometry
Time : 12:10-12:30
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.
S N Pandey
Motilal Nehru National Institute of Technology, India
Title: Morphological studies of virgin and ion irradiated nanostructured BaF2 thin films surfaces
Time : 12:30-12:50
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.
Dragos Victor Anghel
Institutul National de Cercetare-Dezvoltare pentru Fizica si Inginerie Nucleara Horia Hulubei, Romania
Title: Electron-phonon interaction in nanostructures at sub-Kelvin temperaturese
Time : 12:50-13:10
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.
Vladimir K. Mukhomorov
University of Naples Federico II, Italy
Title: To the Question on High-Temperature Superconductivity of Ammonia Systems
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 Ñо-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%.