International Conference and Exhibition on Mesoscopic and Condensed Matter Physics June 22-24, 2015 Boston, USA

Biography:

Nicholas Curro received his PhD in 1998 from the University of Illinois at Urbana-Champaign, and did his Postdoctoral studies at Los Alamos National Laboratory. He then transitioned to a permanent staff member at Los Alamos for several years before joining the faculty at UC Davis in 2008. He has published over 100 papers on NMR studies of the physics of correlated electron systems.

Abstract:

Correlated electron materials exhibit a rich spectrum of unusual ordered states at low temperature, including magnetism, superconductivity, and other exotic ground states. Often the ground state can be tuned by an external parameter such as pressure or field, and in some cases there exists a quantum phase transition that gives rise to a breakdown of conventional Fermi liquid theory in the disordered phase at high temperature. Nuclear Magnetic Resonance (NMR) is an ideal probe these materials because the nuclei offer a window into the microscopic electronic degrees of freedom via the hyperfine coupling. Furthermore, NMR can be performed under a broad range of extreme pressures, fields and temperatures, and is a microscopic in situ probe that does not perturb the electrons. Several examples of the power of this technique to study the phenomena of superconductivity, heavy fermion behavior, and inhomogeneous magnetism will be discussed.

Biography:

Abstract:

In this work the cooperative N2- effect is considered, that is the radiation whose power is ~ N2, where N is the number of emitters which in this case is equal to the number of nonlinear coupled oscillators which model the electrons in a bunch. We consider two different models: in first case the predicted effect is the result of combining two others, namely Gunn-effect in GaAs and undulator-like radiation which can be produced by means of microstructure with grating (microundulator). In the second case, suggested effect is in a sense similar to Dicke superradiance, however it is not the spontaneous phase coherence arising in the ensemble of two-level atoms interacting via the emitted electromagnetic field, but rather, the result of interplay of another two effects. The first one is the ’pumping wave’ acting on the electrons and which is the result of undulator field, while the second is the backward effect of radiation which is produced by electrons moving within such microundulator. As a result, the specific phase coherence (’synchronization’) develops in the ensemble of emitters and they start to generate as a single oscillating charge Ne, while the power of emitted radiation becomes ~N2. It is very probable, that the effect can be used for the developing of a new semiconductor-based room temperature source of the GHz and THz-radiation.

Biography:

Myung Joon (MJ) Han received B.S and Ph.D degree from Seoul National University in 2001 and 2007, respectively. Before coming back to Korea in 2012, he spent his postdoc period in UC Davis, Columbia University, and Argonne National Lab. He is now an assistant professor in Department of Physics, KAIST.

Abstract:

Recently Sr2IrO4 has attracted considerable attention due to the intriguing interplay between spin and orbital degrees of freedom, and its manifestation in the material characteristics. Along this line I will present our recent progress on the iridium oxide and other related compounds based on 4d-/-5d- transition metals. The first example is Rh-doped iridate, Sr2Ir1-xRhxO4, for which the doping dependent metal-insulator transition (MIT) has been reported experimentally and the controversial discussion developed regarding the origin of this transition [1]. We tried to suggest a new picture for understanding the MIT. The second is the artificially-structured iridate superlattice, SrIrO3/SrTiO3. The electronic structure change caused by the interface and the strain was examined in detail and compared with the optical spectra [2]. Finally, I will introduce a fairly different family of compounds, GaT4X8 (T=Nb, Mo, Ta, and X=Se,Te). Interesting similarities with Sr2IrO4 suggests a new possibility for the novel ground states in this series of compounds.

Biography:

A F Isakovic graduated from University of Minnesota in 2003,with thesis on spin transport, after which he joined Cornell University as a Postdoc, studying mesoscopic transport in charge and spin density wave materials. In 2006, he moved to Brookhaven National Laboratory, where his main focus was development of nanofocusing X-rayoptics. He joined Khalifa University, a start-up research university in Abu Dhabi in 2010, where he founded Group for Spintronics, Nanophotonics and Complex Systems, and where he serves as a coordinator for Core Nanocharacterization Facilities.

Abstract:

Minimal energy electronic systems (MEES) have attracted significant attention in recent years due to the variety of fundamental and practical problems arising with the scale down of the components on a chip, broadly addressed via Moore’s law. The MEES design constraint is necessitated, among other processes,by the increase in the release of heat as the size of the active components decreases, which leads to the need to decrease the operating currents, for example. Regardless of the type of device (magnetic memory, electronic switch etc.), nanoelectronic and mesoscopic device physicists are confronted by the number of parameters that need to be optimized in order to minimize the energy (power) expenditure of the device without sacrificing the overall performance. Such problems often involve a number of parameters that make it intractable for nanofabrication and nanotechnology practitioners to cover in a short time scale, which forces the use of an extensive experimentation search combined with an educated guess. In this contribution, we show how a biologically motivated computing technique, such as Particle Swarm Optimization (PSO), can be used to speed up the process of optimal selection of the values of geometric (size) and physical parameters. Specifically, in two examples, we show how critical current needed to perform the switching operation of magnetic tunnel junction (MTJ) and thermoelectric emission current from an anowire could be optimized. A comparison of a computational output with nano-/mesodevice (MTJ or nanowire diodes) literature data shows a good agreement.

Biography:

Leonardo Degiorgi was awarded the title of Professor at ETH Zurich in 2005. He is Coordinator (Delegierter), Department of Physics, and he is head of the Optical Spectroscopy Group at the Laboratory for Solid State Physics. Magneto-optical investigation of strongly correlated systems and of novel materials with peculiar ground states is the main topic of his research activity.

Abstract:

We collect optical reflectivity data as a function of temperature across the structural tetragonal-to-orthorhombic phase transition at TS on Ba(Fe1−xCox)2As2 for x = 0, 2.5% and 4.5%, with uniaxial and in-situ tunable applied pressure in order to detwin the sample and to exert on it an external symmetry breaking field. At T < TS, we discover a remarkable optical anisotropy as a function of the applied pressure at energies far away from the Fermi level and very much reminiscent of a hysteretic-like behavior. Such an anisotropy turns into a reversible linear pressure dependence at T≥TS. Moreover, the optical anisotropy gets progressively depleted with increasing Cocontent in the underdoped regime, consistent with the doping dependence of the orthorhombicity but contrary to the non-monotonic behavior observed for the dc anisotropy. Our findings bear testimony for an important anisotropy of the electronic structure and thus underscore an electronic polarization upon (pressure) inducing and entering the nematic phase.

Biography:

Fengyuan Yang received his PhD in 2001 from The Johns Hopkins University. He is now an Associate Professor in the Department of Physics at The Ohio State University. He is the Chair of the Users Committee of the NanoSystems Laboratory (NSL) and the Associate Director of the Institute for Materials Research (IMR) at The Ohio State University. He has published more than 85 papers in peer-reviewed journals.

Abstract:

Spintronics relies on the generation, transmission, manipulation, and detection of spin current mediated by itinerant charges or magnetic excitations. Ferromagnetic resonance (FMR) spin pumping is a powerful technique in understanding pure spin current. Building on the high-quality Y3Fe5O12 (YIG) films grown by our sputtering technique and the large inverse spin Hall Effect (ISHE) signals enabled by these films, we have characterized spin currents in several classes of materials with different magnetic structures, including: Nonmagnetic (NM) metals, ferromagnetic (FM) metals, nonmagnetic insulators, and antiferromagnetic (AF) insulators. The spin Hall angles determined for a series of 3d, 4d, and 5d NM metals show that both atomic number and d-electron count play important roles in spin Hall physics. By inserting an insulating spacer of various materials between YIG and Pt, we are able to probe the mechanism of spin pumping and the spin propagation. Using several NM insulating spacers, we observed exponential decay of the ISHE voltages in YIG/spacer/Pt trilayers, demonstrating dominant role of exchange coupling in spin pumping. Strikingly, we achieved robust spin transport from YIG to Pt across AF insulators, which initially enhances the ISHE signals and can transmit spin currents up to 100 nm thickness, demonstrating highly efficient spin transport through an AF insulator carried by magnetic excitations.

Biography:

Dr. Lokendra Kumar has completed his Ph.D. at the age of 26 years from C.C.S. University, Meerut, India and postdoctoral studies from CSIR-National Physical Laboratory, New Delhi, India. He is the Assistant Professor of Physics, University of Allahabad (Govt. of India) where his work focuses on the physics of molecular materials and devices. Presently, he is working as a Raman fellow visiting scholar at the School of Electrical and Computer Engineering, Purdue University, USA on the stability issues of organic solar cell technology. He has published more than 40 papers in reputed journals and proceedings. He is serving as a reviewer of several journals

Abstract:

Organic semiconductors (OSCs) offer several potential advantages for the fabrication of low cost ‘Plastic Electronics’ such as Organic Light Emitting Diodes (OLEDs), Organic Photovoltaics (OPVs) and transistors. As Van der Waal’s solids, OSCs form disordered films that results in a large number of defects with in the energy band gap (Eg) which lead the overall photo-physics and performance of devices. Single layer, bilayer and bulk heterojuction (BHJ) OPVs architectures have been studied extensively, but the mechanisms by which these processes improve the devices remain subjects of ongoing debate. Therefore, the understanding of photo-physics is still an important point and needs more discussion. This talk includes, the defect induced optoelectronic properties and exciton physics of organic semiconductors (OSCs) for OPVs. In addition to improved power conversion efficiency, OPVs also need to be sufficiently stable in order to be commercially viable. Ambient atmosphere dependent photovoltaic parameters of OPVs shall be discussed1. Recently, we studied ZnPc/PTCDA bilayer devices2 and the role of nanostructuring of ZnPC surface on photovoltaic properties. It has been observed that nanostructured ZnPc surface in ZnPc/PTCDA bilayer devices shows a considerable improvement in short circuit current density (Jsc) and power conversion efficiency.

Biography:

Ido Kaminer is a Graduate of the Technion Excellence Program, receiving his Bachelor in both Electrical Engineering and Physics. He was granted the Knesset (Israeli Parliament) Award for outstanding undergraduate student achievements in 2007. He has completed his PhD degree in the Physics Department. In his dissertation, he discovered new classes of accelerating beams in nonlinear optics and electromagnetism, for which he received the 2012 Israel Physical Society Prize and the 2014 APS Award for Outstanding Doctoral Dissertation in Laser Science. He is currently a Marie Curie fellow at MIT working in the group of Prof. Marin Soljačić.

Abstract:

The past two decades showed a growing interest in shaping the spatial profile of optical beams by imprinting them with a phase singularity that gives them discrete values of orbital angular momentum. Recently this idea has led to shaping the quantum wavepacket of free electrons, imprinting them with orbital angular momentum and with other intriguing structures. The author show that by shaping wavepackets of relativistic free electrons, fundamental relativistic effects such as length contraction and time dilation can be engineered, leading to the exciting possibility of extending the lifetime of decaying particles. When interacting with matter, the author show how specially designed electron wavepackets create a new kind of ÄŒerenkov radiation, significantly deviating from the conventional ÄŒerenkov Effect. Some of these effects remain even in the classical limit, without requiring a special design of the wavepacket, proving that the well-established ÄŒerenkov Effect contains new phenomena arising directly from the quantum nature of the charged particles. Finally, the author discusses novel phenomena that occur when electrons interact with photons in novel nanophotonic structures. These interactions can lead to novel physical phenomena such as new types of radiation, coherent x-ray sources, and improved detectors for high-energy physics experiments.

Biography:

Hideo Kaiju received his PhD from Keio University in 2005. During the Doctoral course, he worked as a Research Fellow of the Japan Society for the Promotion of Science (JSPS). He worked as a Research Associate from 2004-2007 and an Assistant Professor from 2007-2013 in Research Institute for Electronic Science (RIES) at Hokkaido University. From 2009-2013, he also worked as a Precursory Research for Embryonic Science and Technology (PRESTO) Researcher of Japan Science and Technology Agency (JST). From 2013 to the present, he worked as an Associate Professor in RIES at Hokkaido University. He has published more than 45 papers, including original and review articles. He also received academic awards, including Keio Engineering Society Award in 2000, Applied Physics and Physico-Infomatics Award in 2002, Matsumoto-Hadori Award in 2007, and MRS Best Poster Presentation Award and MSJ Young Scientist Award in 2014.

Abstract:

Recently, we have proposed a new method for the fabrication of nanoscale junctions utilizing thin-film edges. In this method, the edges of two metal thin films are crossed, and molecules, metal-oxide, etc. are sandwiched between their two edges. The junction area is determined by the film thickness, in other words 10 nm thick films could produce 10×10 nm2 nanoscale junctions. This method offers a way to overcome the feature size limit of conventional optical lithography. Moreover, novel spintronics devices, such as large magnetoresistance devices and spin-filter devices, could be created when magnetic materials are used as metal thin films. In this presentation, we report the detail fabrication technique for nanoscale junctions and discuss the structural and electrical characteristics in various nanoscale junctions. The results include the observation of ohmic characteristics in Ni/Ni devices, nanoscale tunneling phenomena in Ni/NiO/Ni devices, and the ballistic regime of nanoscale molecules in Ni/P3HT:PCBM/Ni devices. Moreover, we report ongoing spintronics devices utilizing stray magnetic fields as a new type of spin-filter device. This device consists of inorganic complexes or quantum dots (QDs) sandwiched between two crossed edges of magnetic thin films. In this structure, a high magnetic field could be locally generated in the inorganic complexes or QDs due to the contributions of the stray field from both edges of the magnetic thin films. Since a large magnetic field produces a large Zeeman effect, energy splitting of the inorganic complexes or QDs can be enhanced. Therefore, a large spin-filter effect can be expected. In this talk, we will focus on the structural and magnetic properties in our proposed nanoscale spintronics devices.

Biography:

KK has completed his Ph.D from TU Berlin working a the Hahn-Meitner Institut, Berlin. He joined the Institute for Solid State Physics of the University of Tokyo as an assistant professor and became a professor in 1997. He was the Director General of the QuBS Directorate at the JAEA until 2014 and now serves as a Senior Consultant in the QuBS Center, JAEA.

Abstract:

The recent development of neutron scattering techniques, especially polarized neutron scattering utilization, will be reported with examples from the recent investigations on mutiferroic materials. The recent discovery of the spin-driven ferroelectricity triggered intense exploration of new multiferroic materials and research of the novel magneto-electric effect in condensed matter. In studying these advanced functional materials, one is permanently confronted with complex spin configurations, for example, non-collinear, incommensurate magnetic structure such as helimagnetic or cycloidal spin structure as a result of frustrated magnetic interactions. Since the giant functional responses in these materials are direct consequences of these complex magnetic structures breaking the inversion symmetry, the detailed knowledge of the spin structure is mandatory to understand the essence of these advanced magnetic functional materials. More recently an electric-dipole-active magnetic excitation, often termed as electromagnon, has been observed in these multiferroic materials. The polarized neutron technique, in addition to the conventional unpolarized neutron scattering, can greatly contribute to obtain deep insight into these complex spin structures and excitations. The examples include investigations on ferroelectricity induced by a proper screw-type helical spin ordering in Ga-doped CuFeO2 and electromagnon in the Y-type hexaferrite Ba2Mg2Fe12O22 with transverse conical spin structure. These investigations were performed in collaboration with S. Wakimoto and M. Takeda, Quantum Beam Science Center, Japan Atomic Energy Agency, Japan; T. Nakajima, T. Arima, Y. Taguchi, Y. Tokunaga, Y. Kaneko and Y. Tokura, Center for Emergent Matter Science, RIKEN, Japan, N. Terada and H. Kitazawa, National Institute for Materials Science, Japan; S. Mitsuda, Dep. of Physics, Tokyo University of Science, Japan; S. Ishiwata, Department of Applied Physics, University of Tokyo, Japan; D. Okuyama, IMRAM, Tohoku University, Japan ; M. Matsuda and J. Fernandez-Baca, Quantum Condensed Matter Division, Oak Ridge National Laboratory, USA.

Biography:

Abstract:

The 1H spin-lattice and spin-spin relaxation time as well as high data point density 1H–31P cross-polarization kinetics (static and upon MAS) measurements have been carried out for calcium hydroxyapatite containing amorphous phosphate phase (ACP-CaHA) and nano-structured hydroxyapatite (CaHA). The chosen setting of the sampling frequency of 5×104 s–1 allowed to reveal all spin interactions having the dipolar splitting b£25 kHz that in the case of 1H–31P interaction means the structures with the internuclear distances r³0.125 nm could be resolved. The advanced processing of CP MAS kinetic data has been developed introducing the variable cut-off distribution of the dipolar coupling. This procedure allows to describe the oscillatory kinetics and CP curves in nano-structured materials over a wide range of contact time and to determine the characteristic size profile and composition of the spin clusters. The characteristic size of 31P–(1H)n spin nano-cluster being within 0.3¸0.5 nm has been determined for nano-structured CaHA. The 1H spin-lattice and spin-spin relaxation time measurements revealed the fast spin motion takes place in ACP-CaHA. The effect of MAS rate on the 31P signal shape confirms that the correlation time of this motion gets into the time scale of microseconds or even nanoseconds. Such fast dynamics can be attributed to the rotational diffusion of adsorbed water molecules. The magnitude of the inhomogeneous anisotropic broadening of 1220±20 Hz determined for nano-structured sample is very close to 1185 Hz that corresponds to the maximum of Gauss distribution of dipolar 1H–31P coupling obtained using 31P–1H CP MAS kinetics. The dynamics of this interactions runs in the time scale of microseconds and it is much slower that in ACP-CaHA.

Biography:

N Foy is actually completing his PhD thesis dedicated to the theoretical, numerical and experimental studies of the contact between metallic bodies under severe mechanical compression, paying a special attention to their applications to railway transport (power supply-train propulsion).

Abstract:

Many industrial applications, such as power transfer systems for train propulsion or mechanical contact between solid surfaces, involve multi-contact interfaces (MCI). This challenging field has attracted the attention of many researchers and engineers attempting to build a complete and coherent description of such interfaces. This field offers a natural framework for complexity studies since MCI involve both tribological, mechanical and physical processes intimately intricated at different scales. Through the strong coupling between different classes of properties, that complexity is also the main obstacle towards a comprehensive understanding of the Physics of MCIs. In accordance with the common trends in the field, we propose a theoretical approach to the electrical transport through metallic MCIs, treated as a discrete collection of a large but finite number of contacting asperities (mechanical spots due to surface roughness), and taking into account its natural coupling with thermal transfer. A first one-spot model is derived, leading to the temperature (current) dependence of the constriction resistance of individual spots. We predict a critical current depending on the spot size and thermal conductivities of the metal pieces and controlling the transition to a highly resistive state of the interface. Extension of the model to a many spots interface is briefly discussed. The results are finally confronted with experimental data regarding a two-bead system revealing a very good agreement with the model. Implications of the model on the mechanism of the so-called Branly effect are also discussed along with the likely influence of tunneling between the contacting solids.

Biography:

Puneet Srivastava received his PhD degree from IMEC-Belgium in 2012. During his PhD, he worked on the fabrication and technology integration of GaN-on-Si HEMTs for power switching applications. Since September 2012, he has been working as a Postdoctoral Associate in Electrical Engineering and Computer Science at MIT, USA with Prof. Tomás Palacios in the area of high frequency GaN-electronics. He has authored/co-authored over 40 international publications and holds 2 patents. He serves as an Editor for IETE-Technical Review and a Member of IEEE and IEEE Electron Device Society (EDS). He is a Reviewer of various journals such as IEEE Electron Device Letters, IEEE Transaction on Electron devices among others.

Abstract:

Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs)has been identified as essential components for realizing efficient, compact, high power switching systems and high power amplifiers at high frequencies for low loss power conversion and transmission. In the recent years, significant advancements have been made towards GaN-on-Si power devices due to the lower cost and large size availability of the Si substrate. Si substrate, however, presents constraints such as limited voltage handling capabilities, which are more apparent at elevated temperatures. In my talk, I will discuss a novel technology solution of Si substrate engineering to mitigate the high voltage and high temperature restrictions imposed by Si for power electronics applications with an improved device figure of merit. Several kilo Volt devices have been achieved in a cost effective way with high temperature capabilities required by various demanding applications such as downhole tools in oil and gas industry, automobiles and photovoltaics among others. The second part of my talk will focus on developing a unique technology with a deep sub-micron gated large periphery GaN-HEMTs with high power density for future kilo Watt Radio Frequency (RF) amplifier systems.

Biography:

Akira Ishibashi completed his PhD in 1990 from Dept. of Phys., the University of Tokyo. He joined Sony Corp. Res. Ctr., 1983 and achieved the world first room-temperature CW operation of blue laser diode based on ZnMgSSe II-VI materials in 1993. He was a visiting faculty of Loomis Lab., Dept. Phys., Univ. of Illinois at Urbana-Champaign, 1990-1991, and a visiting Professor at Inst. for Interdisciplinary Research, Tohoku Univ. in 1998. Since 2003, he has been a Professor heading Nanostructure Physics Lab., RIES, Hokkaido University.

Abstract:

New devices and systems in materials science (atoms), information technology (bits), energy, renewable energy, and environment engineering having been of increasing importance, it would be convenient for us to investigate those new devices and systems in the four-dimensional space of atom-bit-energy/environment (ABE2) space. We have been studying quantum-cross devices in atom-bit (AB)-plane, multi-striped orthogonal photon-photocarrier-propagation solar cell (MOP3SC) in bit-energy (BE)-plane, and clean unit system platform (CUSP) in atom-environment (AE)-plane. The CUSP, being itself a key player in AE plane of the ABE2 space as a clean versatile environment of ISO class -1 to 5 having small footprint, low power-consumption and high cost-performance can serve as the next generation production system and future cross-disciplinary platforms including the one for kinetosomnogram. Multiply-connected CUSP system will outperform conventional clean room only for nanotechnologies or bio-technologies but also for the next-generation environment-friendly healthcare platform. Since extremely high cost-performance in industrial and social activities means “cost/performance ~ 0”, which could be a counterpart of “mass ~ 0” in physics, CUSP would be able to serve as a “Nambu-Goldstone boson” to make a social phase transition for our better world in terms of maintaining high QOL and postponing the time when elder people might get into medical cares. The CUSP in AE plane, outperforming the conventional super clean room (“main frame”), would be the clean space for all of us in near future.

Biography:

Takashi Kimura is a Research Scientist in the field of spintronics. He got his BEng in Electronics, MEng in Nano-Electronics and PhD from Osaka University. He was a Research Fellowship in Riken and was Assistance Professor in Institute for Solid State Physics, University of Tokyo. Now, he is a Professor for Department of Physics, Graduate School of Sciences and the Director of Quantum Nano-Spin Sciences Research Center, Kyushu University, Japan. He was awarded the IUPAP Young Scientist Metal in the field magnetism 2009.

Abstract:

Manipulation of spin current is a central issue in the operation of spintronic devices because the spin current plays key role in spin-dependent transports and spin-transfer switching. Recently, heat utilization for creating the spin current has been paid considerable attention, leading to an emerging field, spin caloritronics. Various mechanisms for generating spin current utilizing heat such as the spin Seebeck effect, spin dependent Seebeck effect, Seebeck spin tunneling effect and spin heat accumulation have been demonstrated in different device structures. However, the generation efficiencies for spin current were much smaller than that by electrical means, indicating quite far from the practical application. Recently, we have shown that the thermal spin injection efficiency was dramatically enhanced by using a CoFeAl injector because of its favorable band structure. This demonstration may open a new avenue for the utilization of the spin current in the nano-electronic devices. In this presentation, the author will introduce an electrical and thermoelectric property for the excellent material CoFeAl and show that a sign reversal of the Seebeck coefficient between the up and down spins is the key for enhancing the generation efficiency of the spin current. Furthermore, we show that CoFeAl induces a large spin Peltier effect.

Biography:

Dr. 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.

Abstract:

We propose a comparatively simple way to fabricate a metamaterial which is both gyrotropic and of 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 nano-particles, immersed in a mixture of other two, silver and mercury cadmium telluride. In the work we carried out computer simulations in the frame of the proposed model in order to establish the domains of existence of such material searching through the vast parameter space. The main result of the paper can be summarized as follows. In the framework of the model, we succeeded in establishing the domains of gyromagnetic metamaterial existence, relative to all parameters characterizing the model that is, temperature, external magnetic field, parameters of nano-particles, and fraction of cadmium in Hg 1-xCdx Te - compound as well as the relative concentrations of the mixture components. Negative refraction and optical activity can be achieved only if the material is in external, however moderate magnetic field. On the other hand, in some circumstances, it could be an advantage, since switching magnetic field on and off, one can trigger off negative refraction.

Biography:

Dr. P.R Alapati obtained his Ph. D degree in Physics during 1988 from Nagarjuna University, India by working in the field of Liquid Crystals for my thesis on structural and phase transition studies in Schiff base liquid crystal monomers. After carrying out postdoctoral research at the university of Southampton, The United Kingdom on a Commonwealth scholarship and SERC, UK fellowship for two years, he joined North Eastern Regional Institute of Science and Technology, Itanagar, Arunachal Pradesh, India (a Deemed to be university established and fully funded by Government of India) as a lecturer in 1991. Working as professor since 2009.

Abstract:

We report here the study of molecular dynamics in two liquid crystal dimer compounds of the homologous series α, ω – bis (4 – alkyl aniline benzylidene 4’ –oxy ) alkane series (m.OnO.m) using Raman Spectroscopy in the spectral region 1000-1735 cm-1 as a function of temperature. The compounds 6.O6O.6 and 6.O12O.6 were synthesized following a standard procedure available in literature and characterized using Differential Scanning Calorimetry and Polarizing Thermal Microscopy. The Raman spectra of these compounds were recorded at different temperatures using a Triaxmonochromator equipped with a CCD detector in the 1000-1735 cm-1 region. The spectra were recorded over a wide range of temperature starting from room temperature (crystalline phase) to 180°C (isotropic phase) for 6.O6O.6 and to 132°C for 6.O12O.6 at intervals of 0.1°C near the phase transition temperature and at 2°C elsewhere. The compound 6.O6O.6 exhibits SmA and SmF phases, whereas compound 6.O12O.6 exhibits the nematic phase. The precise values of peak positions, integrated intensities and line widths of some selected Raman bands have been obtained by curve fitting and deconvolution using GRAMS software. The changes in the molecular alignment and its effect on inter/intra molecular interactions at different phase transitions have been discussed and compared in this paper on the basis of variations in the Raman parameters with temperature. An important finding from our studies is that the compound 6.O6O.6 exhibits a rigidity that is similar to monomeric liquid crystalline systems like MBBA or TBBA, but very much unlike other dimmers, which possibly could explain the phase behavior of these symmetric dimers in comparison with liquid crystal monomers.

Biography:

Jan Smotlacha has completed his PhD at the age of 33 years from Czech Technical University. Now he works as the in the Bogoliubov Laboratory of Theoretical Physics in the Joint Senior Research Scientist Institute for Nuclear Research in Dubna. He has published about 10 papers in reputed journals or conference proceedings.

Abstract:

The graphene nanostructures are the materials derived from the hexagonal carbon lattice. Its structure can be changed by the supply of different kinds of defects, especially the pentagons or the heptagons. In this way, new materials are created – the fullerenes (nanospheres), nanotubes, nanocylinders, nanoribbons, nanocones, nanohorns, nanotoroids, nanowires etc. A wide variety of electronic and magnetic properties of these structures have been studied. They promise a potential use in nanoscale devices like quantum wires, nonlinear electronic elements, transistors, molecular memory devices or electron field emitters. One of the main characteristics of the electronic properties is the local density of states which gives the number of the electron states per the unit interval of energies and per the unit area of the surface. There are more ways how to calculate this quantity: By the direct calculation from the electronic spectrum, using the Green function method, by the application of the continuum gauge field-theory approximation etc. In our investigation, all the 3 methods were used: The continuum gauge field-theory approximation was used for the calculation of the electronic properties of the surface with the hyperboloidal geometry in the vicinity of the pentagonal and heptagonal defects, the Green function method and the energy spectrum were used for the calculation of the electronic properties of the nanocylinders and of the disclinated nanoribbons. Our latest research is connected with the properties of the graphene wormhole and the possibility of its construction. We are also interested in the effect of the spin-orbit interaction in the graphitic nanocone, in its influence on the local density of states and in possible application of this effect in atomic force microscopy.

Biography:

Beer Pal Singh has received his M.Phil. (1998) and Ph.D. (2002) from C.C.S. University, Meerut (UP), India. He is holding faculty position in Physics at C.C.S. University, Meerut since 2004. Presently, he is working as a visiting scientist (Raman Fellow) in University of Puerto Rico, Mayaguez, PR, USA. He has supervised 6 Ph.D. and more than 20 M.Phil. students for their research thesis. He has published more than 25 papers in reputed journals and serving as a reviewer of several national/international journal of repute. Recently, he has been nominated as an editorial advisory board member of Vigyan Pragati published by NISCAIR, New Delhi.

Abstract:

Thin films of sulfide semiconductor are very important for their efficient use in the fabrication solar cells and optoelectronics devices. The properties of vacuum evaporated thin films of sulfide semiconductors are very sensitive to the deposition conditions. Vacuum thermal evaporation is very simple and inexpensive method which can be used for large area thin film deposition. The problem associated with this technique is to maintaining the stoichiometry in the deposition of compound semiconducting materials composed of elements having different vapor pressures. Generally the vacuum deposited thin films of compound sulfide semiconductors have deficiency of sulfur. Such non-stoichiometric films lead to defects in the crystalline structure which, adversely affect the electro-optical properties of the films. Thin films of compound sulfide semiconductors (CdS, ZnS and PbS) have been deposited in a low ambient atmosphere of H2S by thermal vacuum evaporation technique. Thiourea has been used to create an ambient atmosphere of H2S inside the vacuum chamber during evaporation. The higher reactivity of H2S will ensure a better conversion of the dissociated cations (sulfide ions) into compound sulfide semiconductors. The impact of ambient H2S atmosphere on the growth and properties of vacuum evaporated sulfide thin films have been studied via optical spectroscopy, XRD, SEM, EDX, AFM and XPS measurements. The films grown in H2S ambient atmosphere are more uniform, more adhesive, pin hole free and have better crystallinity and better adhesion to the substrates and would be inherently more suitable for any electro-optical device fabrication.

Biography:

Dr. Prober is a Professor of Applied Physics and Physics at Yale University. He joined the faculty in 1975 as an Assistant Professor, after completing the Ph.D. in Physics at Harvard. He was promoted to tenure in 1981. He received the A.B. in Physics from Brandeis University in 1970. His main research interests are in nanosystems, superconductivity, quantum noise and low temperature photon detectors.

Abstract:

Graphene has recently been proposed as an ultrasensitive THz photon detector for space-based astronomy observations. We have studied the thermal properties of monolayer graphene for this application, and done extensive modeling of the detection processes. We employ superconducting contacts to achieve energy confinement in the graphene. Recently we have studied experimentally the energy loss processes in graphene down to T=0.1 K. The space-based observatories that could employ such detectors will be discussed, as well as the science that can be done with these observatories.

Biography:

Yasutami Takada has completed his Ph.D on mechanisms of superconductivity in degenerate semiconductors at the age of 28 years from Tokyo University and postdoctoral studies from Purdue University and University of California at Santa Barbara. In 1985, he joined in the division of Condensed Matter Theory, Institute for Solid State Physics, University of Tokyo as a faculty member and is now a professor at the division concurrently with a professor at Center of Computational Materials Science. He has published more than 110 papers in reputed journals and served as a Divisional Associate Editor of Physical Review Letters during 2001-2007.

Abstract:

Hydrogen in metals has attracted attention for a long time from both basic scientific and technological points of view. Its electronic state has been investigated in terms of a proton embedded in the electron gas mostly by the local density approximation (LDA) to the density functional theory (DFT). At high electronic densities, it is well described by a bare proton H+ screened by metallic electrons (charge resonance), while at low densities two electrons are localized at the proton site to form a closed-shell negative ion H- protected from surrounding metallic electrons by the Pauli exclusion principle. However, no details are known about the transition from H+ to H- in the intermediate-density region. In my talk, I shall explain its complete picture, in particular, a sharp transition from H+ screening charge resonance to Kondo-like spin-singlet resonance, the emergence of which is confirmed by the presence of an anomalous Friedel oscillation characteristic to the Kondo singlet state through diffusion Monte Carlo (DMC) calculations with total electron number up to 170. This picture enriches the paradigm for metallic screening to a point charge with the addition of a possibility of spin resonance with a very long screening length, depending on the metallic density and the magnitude of charge. Besides, this work reveals that hydrogen is most stably embedded in the form of this spin-singlet resonance state, which may be important information for hydrogen storage in metals.

Biography:

Tsuyoshi Takami has completed his PhD in 2007 from Nagoya University and worked as a Postdoctoral Researcher at University of Texas at Austin. He was the editor of Nanothermectricoels. He has published more than 35 papers in reputed journals such as PRL, PRB, and APL and a comprehensive review book titled “Functional Cobalt Oxides: Fundamentals, Properties, and Applications” in the CRC Press, Taylor & Francis Group.

Abstract:

Self-organization has attracted much attention because of its tremendous promise. Well-known examples of self-organization include the double-helix structure of DNA and the three dimensional structure of protein. Universe, creatures, and materials are also regarded as a form via self-organization spreads over spatiotemporal, giving or taking energy and information; there is a broad range of new fields to be created. Recently, the author found the single-crystal synthesis method and coexistence of multiple phases such as metallic and semiconducting phase, spin cluster and non-magnetic phase, and intermediate-spin and low-spin phase due to self-organization. The former synthesis method becomes to be possible by self-organization of atoms or molecules and the latter coexistence originates from that of electrons. This physical phenomenon is expected to be beneficial not only for exploring novel physical properties but also for improving functionality. For example, hydrogen, the simplest and most abundant element in the universe, has the potential as an energy carrier. New hydrogen storage material, meets the energy need today, has been synthesized by self-organization.

Biography:

Xiaoming Wen has completed his PhD in 2007 from Swinburne University of Technology, Australia. He performed postdoctoral studies at University of Melbourne in Australia and Academia Sinica in Taiwan. He is currently a research fellow in Australian Centre for Advanced Photovoltaics, University of New South Wales. He has published more than 80 papers in refereed journals. His research includes ultrafast time-resolved spectroscopy and photophysics of nanomaterials, particularly focuses on photoexcited carrier dynamics in nanomaterials (metal nanoclusters and carbon nanodots and advanced photovoltaics.

Abstract:

Mixed organic-inorganic halide perovskite has emerged as very attractive high efficiency solar cells over the past few years. Significant progress has been achieved such as the most recent demonstration of independently certified efficiency of 20.1%, attribute not only the device structure, and superb light absorption, decent ambipolar charge mobility and less excitons binding energy compare with organic solar cells. The device design and performance improvement critically depend on the physical understanding, in particular, the carrier dynamics at various timescale. Despite the rapid progress in demonstrated efficiencies perovskite solar cells, there exists a gap in the fundamental understanding of the carrier dynamics such as generation; transport; and extraction. Here we systematically investigate the carrier dynamics in organic-inorganic halide perovskite CH3NH3PbI3 in the various timescale using steady state and time-resolved spectroscopy. Our investigation reveals both steady state PL and time-resolved PL is closely relevant to the excitation intensity. The carrier dynamics can be determined by the processes of carrier relaxations, such as free carrier recombination, exciton recombination, defect/surface trapping, relaxation of the trapped carriers, Auger recombination, charge migration and phase transition. An evident state filling is observed using ultrafast transient absorption. At low excitation density, defect/surface trapping and electron-hole recombination are the major processes. Therefore, an excitation density relevant carrier dynamics can be observed in photoluminescence (PL) decay by using time correlated single photon counting (TCSPC). A nonlinear relation between the excitation and emission intensity is also identified in the steady state PL by , withβ>1. Theoretical modelling reveals that the nonlinearity is determined by both the relaxation rate and density of the defect states; and thus relevant to the fabrication. Moreover, the variation of the carrier density with time, due to carrier migration and phase transition, is closely related to the carrier dynamics. Interestingly, charge detrapping, charge migration and accumulation result in a much slow process in milliseconds to seconds. In contract, at high density of excitation the saturation of the defect states and enhanced Auger nonradiative recombination becomes the dominant mechanism. The decreased PL efficiency and fastened carrier dynamics were observed in steady state and TRPL, respectively. It is confirmed that carrier dynamics is also closely correlated with the fabrication and morphology of the films.

Biography:

Yuko Ichiyanagi is an Associate Prof. at Yokohama National University since 2009 (Applied Physics). Since 2007 she was concurrently a researcher of Precursor Research Embryonic Science and Technology of Japan Science and Technology Agency, and developed magnetic nanoparticles for biomedical applications. She chaired at several international conference. She got a prize of Industrial Times at 9th Annual Meeting of Society of Nano Science and Technology in 2011. Now she has published more than 50 papers and books. In recent year she focused on the magnetic nanoparticles for biomedical applications and was successful.

Abstract:

Recently, magnetic nanoparticles (MNPs) have attracted attention as they have potential medical applications, such as in MRI contrast agents, drug delivery systems (DDS), and in hyperthermia treatments. Magnetic ferrite nanoparticles encapsulated in amorphous SiO2 were prepared using our original wet chemical method. In these magnetic nanoparticles, Si ions are located on the surface, and because of this characteristic structure particles were functionalized by amino-silane coupling procedure. We tried to introduce these functional particles into the living cells, and these particles were localized by the external magnetic field. Then cancer cell selective particles were further developed by attaching folic acid. In order to estimate heating effect of magnetic nanoparticles, AC magnetic susceptibility was measured. The imaginary part of the AC magnetic susceptibilities, χ”, depending on the frequency, field, and particle size were analyzed. The most efficient heat dissipation can be predicted for the MnO.8ZnO.2Fe2O4 sample of particle size 18 nm. It was found that this sample followed Néel relaxation system. Then the temperature of samples was measured upon AC magnetic field of 151 Oe, 15 kHz at 310 K. The rise in temperature was found high enough to destroy the cancer cells. In vitro experiment was carried out for the cultured cancer cells. An extensive hyperthermia effect was observed, and thereby concluding that this sample is an effective agent of hyperthermia treatment.

Biography:

Prof. Ajay Kumar Mishra is currently working as Professor at Nanotechnology and Water Sustainability Unit, College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, Johannesburg, South Africa. He is also working as “Adjunct Professor” at Jiangsu University, China. Prof. Mishra has pursued PhD in Chemistry from Department of Chemistry, University of Delhi, Delhi, India. In 2006, he moved to the University of Free State, South Africa for Postdoctoral studies in the area of composites/nanocomposites. Later in 2009 Prof. Mishra has joined Department of Applied Chemistry as Senior Lecturer where he was promoted to Associate Professor in 2011. Prof. Mishra is currently group leader of the research area for the composites/nanocomposites, water research and bio-inorganic chemistry. He has hosted several visiting researchers/scientists/postdocs in his group. Prof. Mishra has also developed a number of collaborations worldwide. His research contribution includes many publications in international journals. He has delivered a number of including Plenary/Keynote/Invited Lectures. For his outstanding research profile, he was awarded a number of awards. Prof. Mishra also served as Associate Editor as well as member of the editorial board of many international journals. He has edited several books by the renowned publishers. He has been reviewing a number of international journals and member of a number of scientific societies.

Abstract:

Presently clean and safe drinking water is a prior requirement of the society. Water pollution due to toxic metals and organic compounds remains a serious problem to the environment and public health. Heavy metal ions, and dyes are often found in the environment as a result of industrialization. They are known to be common contaminants in wastewater and many of them are highly toxic. Thus, there is a need to develop technologies that can remove toxic pollutants found in wastewaters. Several methods are available; including membrane technology, but adsorption is one of the more popular methods for the removal of pollutants from the wastewater. Biopolymers represent an interesting and attractive alternative as adsorbents because of their particular structure, physico-chemical characteristics, chemical stability, high reactivity and excellent selectivity towards aromatic compounds and metals. Adsorption on biopolymers and their derivatives are known to remove pollutants from water. The current focus of the talk will be the recent advancement in nanocomposites with the synthesis of adsorbents containing polysaccharides, in particular modified biopolymers and also the advantages of the removal of pollutants from the wastewater.

Biography:

Agnieszka Wolos has completed her PhD in 2005 from the University of Warsaw, Faculty of Physics. In 2005-2006 she was a Post-Doc at the Johannes Kepler Universität Linz, Institut für Halbleiter- und Festkörperphysik. She is now an Assistant Professor at the Institute of Physics Polish Academy of Sciences and at the University of Warsaw. She is interested in electron paramagnetic resonance, in particular in the application to studies of the electron transport phenomena. She currently works on topological insulators

Abstract:

It has been recently discovered that bismuth chalcogenides, previously recognized for its thermoelectric properties, hide a surprise in the band structure - topologically protected surface states. They are so-called three-dimensional topological insulators constituting a new state of quantum matter. They possess a band gap in the bulk and metallic surface states resulting from the change of the topological invariant at the interface with other material (could be the vacuum). The crystal structure of bismuth chalcogenides hosts considerable amounts of lattice defects, which results in highly conducting bulk covering the surface electric transport. In order to investigate properties of both the bulk and the surface states, Bi2Te3, Bi2Se3, and Bi2Te2Se were grown by the vertical Bridgman method at the Institute of Electronic Materials Technology, Warsaw. Undoped Bi2Te3 is p-type due to bismuth anti-sites while Bi2Se3 is n-type due to selenium vacancies. The structure of Bi2Te2Se prevents formation of both types of defects, resulting in the lowest conductivity of all the three materials. The conductivity of Bi2Se3 was reduced by varying the stoichiometry and applying calcium acceptor doping. The limits for the reduction of the bulk concentration will be discussed. Bulk and surface states were investigated using the contactless microwave spectroscopy (with the use of a standard electron paramagnetic resonance spectrometer). Properties of the bulk conduction electron spin resonance will be presented, while the presence of the surface states is manifested in the cyclotron resonance and weak anti-localization phenomena.

Biography:

Hong-Chen Jiang has completed his PhD from Tsinghua University in China, and Postdoctoral studies from Microsoft Research Station Q and Kavli Institute for Theoretical Physics in University of California at Santa Barbara. After that, he spent half a year in University of California at Berkeley. Now, he is a Staff Scientist of Stanford Institute for Materials and Energy Science of SLAC National Accelerator Laboratory and Stanford University.

Abstract:

Quantum spin liquids (QSLs) are elusive magnets without magnetism, resisting symmetry breaking even at zero temperature due to strong quantum fluctuations and geometric frustration. The simplest QSLs known theoretically are characterized by topological order, i.e., topological QSL, and support fractionalized excitations. However, there is no practical way to directly determine the topological nature of the states. In my talk, I will introduce a simple and practical approach, i.e., cylinder construction, to identify topological order by entanglement entropy. As an example, by extracting accurate topological entanglement entropy (TEE), we identify the quantum spin liquid ground states with topological order in the antiferromagnetic spin-1/2 Heisenberg model on the Kagome lattice. Finally, I will also try to talk about the finite-size corrections to TEE, and its relevance to QSLs, as well as future searches for topological ordered phases.

Biography:

Mengyan Shen is an Associate Professor of Physics at University of Massachusetts Lowell. He obtained his PhD from University of Science and Technology of China in 1990, and his MS and BS from Inner Mongolia University in 1987 and 1984, respectively. He has published about 100 research papers. He has served as reviewers for different journals and foundations. In September 2006, he resigned his faculty position at Tohoku University and joined University of Massachusetts Lowell to further develop nano manufacturing techniques using intense femtosecond laser pulses together with students and fellow researchers. In addition to research work, he has experience teaching and leading experiments for undergraduate and graduate students in China, Japan and United States.

Abstract:

For many years, researchers had endeavored to replicate natural photosynthesis converting carbon dioxide and water to hydrocarbons and carbohydrates. In their approaches, the efficiency of solar energy storage was very low and there had been no significant progress towards large-scale and highly efficient artificial photosynthesis. Pulsed laser-assisted etching is a simple but effective method for making small regular structures directly onto a solid surface. We have successfully fabricated sub micro- or nano-meter sized structures on different solid surfaces immersed in liquids with femtosecond laser pulse irradiations. We can control the experimental conditions to design and make nanostructures in different materials and on the surfaces with different morphologies. We have combined the plasmonic and the catalytic properties of metal nanostructures to obtain an efficient artificial photosynthesis, converting carbon dioxide and water into hydrocarbons for solar energy storage. In our experiments, we have discovered a highly efficient artificial photosynthetic process that utilizes cobalt (Co) or iron (Fe) nanostructures formed by the femtosecond laser pulse irradiation. The details of this discovery will be introduced and discussed in the talk.