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

M A Rastkhadiv has completed BS and MS from Shiraz University and now is finalizing his PhD from Shiraz University, School of Science. He is interested in statistical mechanics and is researching on quantum many body systems in nano dimensions.

Liquid 3He injected in a carbon nanotube is of high interests due to different behavior of the liquid helium in the quasi-one dimensional system. In this work, a variational approach based on the cluster expansion of energy has been performed to calculate some thermodynamic properties of this quantum system. In order to do so, a single-walled carbon nanotube (SWCN) containing liquid 3He is considered, applying the Lennard-Jones and Stan-Cole potentials for 3He-3He and 3He-C interactions, respectively. We have done our calculations for density range 0.1-1.0 nm-1 and radii R=0.3, 0.48 and 0.8 nm. At first, we have calculated the one-body (E1) and the two-body (E2) energies, then the total energy (E=E1+E2) has been obtained. Our results show that the one-body energy has negative values while the two-body energy has positive values, although both of them increase by increasing density. To compare our results with other works, we have calculated single particle energy states ε(kρ,φ) for a single 3He atom in a SWCN in ground state nρ=1 , nφ=0 equal (-231.671 K) for radius R=0.48 nm, where there is a good agreement between our results and Vranjes et al. The total energy is negative for all the densities. We have calculated the equation of state for the system, and have found out that the pressure increases by increasing the density and nanotube radius. Our results for incompressibility show that the system can have a liquid state for higher densities (higher than 1.0 nm-1) for R=0.48 and 0.8 nm whereas for R=0.3 nm cannot have a liquid-gas phase transition. These transition points occur in densities about 1.2 and 2.1 nm-1 for 0.8 and R=0.48 nm-1 radii, respectively; which are very low densities. In other words, liquid 3He in a carbon nanotube is the lowest density liquid one has ever seen. This helps us to make 3He liquid in very low densities in comparison with three dimensional systems.

Suraka Bhattacharjee has completed her BSc from University of Calcutta and MSc from Presidency University in the year 2014. Currently, she is pursuing her PhD from S N Bose National Centre for Basic Sciences, India, under the supervision of Dr. Ranjan Chaudhury. Her first paper has been recently published in Physica B.

The doped quantum Heisenberg antiferromagnets are extremely alluring for their interesting magnetic properties and inherent itinerant character. Even the magnetic behaviors of the one-dimensional and two-dimensional antiferromagnets are quite distinct which is in contrast to the age old idea of the theoreticians and experimentalists. The strongly correlated t-J model is the simplest model that has paramount importance in describing these itinerant systems starting from the slightly less than half-filled band limit. My work is primarily based on the calculation of generalized spin stiffness constant for low-dimensional doped antiferromagnets corresponding to the t-J model. The results can vividly elucidate on the characteristic magnetic features of doped La2-xSrxCuO4 or YBa2Cu3O6+x which are known to exhibit high temperature superconductivity at optimal doping concentration. While the generalized spin stiffness constant for 2-D systems shows a monotonous fall with increase in doping concentration, the spin stiffness in 1-D shows a peak in the lower doping region. The comparison of my results with other theoretical and experimental results substantiates the inextricable role of spin stiffness constant as effective exchange constant for these doped itinerant antiferromagnets at least in the low doping region. Moreover, the plot of spin stiffness constant versus doping concentration for 2-D systems shows a cross-over or a point of inflexion near 61% doping concentration, signifying a possible quantum phase transition, as was previously shown by Emery et al. Finally, it can be concluded that my formalism also puts forward a novel scheme for determining the exchange constant and magnetic correlations in the strongly correlated itinerant magnetic systems.

Vladimir V Rumyantsev is Professor in Nanophysics Department at Donetsk National University (DonNU) and Head of Physics Technology Subdivision at Donetsk Institute for Physics and Engineering (DonPhTI). He received PhD in Physics (1988) from DonNU and Doctor of Science in Solid State Physics (2007) from DonPhTI. He has published more than 200 scientific publications. He is Group Leader of International project in the framework of the European program FP7-PEOPLE-2013-IRSES (2013-2016).

Fabrication of novel materials for the creation of sources of coherent radiation is presently a vast interdisciplinary area of theoretical and experimental investigations, which involve condensed matter physics, nanotechnologies, chemistry as well as information science. In this connection, some promising vistas can be opened by the so-called polaritonic crystals, which represent a particular type of photonic crystals featured by a strong coupling between quantum excitations (excitons) and electromagnetic waves. The important features of photonic band-gap structures under discussion are connected with ‘slow’ light, which is one of the promising fundamental physical phenomena that can be explored in the design of various quantum optical storage devices. In particular, the effective reduction of the group velocity demonstrated in the associated optical waveguide resonators. Based on the representations of the ideal photonic structures, the non-ideal systems of this class - polaritonic crystal, which is a set of spatially ordered microcavities containing ultracold atomic clusters, is considered. Moreover, the spatial distribution of cavities (microresonators) is translation invariant, and the atomic subsystem has randomly distributed defects: Impurity atomic clusters (quantum dots) or a vacancies. Numerical modeling of dependence of the dispersion of polaritons in this imperfect lattice of associated microresonators on impurity concentration is completed. Using the virtual crystal approximation, the analytical expressions for polaritonic frequencies, effective mass and group velocities, as a function of corresponding quantum dots and vacancies concentrations, is obtained. It turned out that even with a small number of vacancies in the lattice (one position for a thousand resonators) weight polaritons increases by three orders of magnitude. These results enable to extend the possibility of creating a new class of functional materials - polaritonic crystal systems.\r\n\r\n

Shams B Ali has completed her MSc from University of Technology, Laser Physics Department, Iraq and now studies PhD at Newcastle Upon Tyne University, UK. She has published 5 papers in reputed journals.

This research concerns the physical and structural properties of carbon nanotube/conductive polymer composites and their use in gas sensors. A good sensor should be sensitive, reliable and low cost, with fast response and a short recovery time. Carbon nanotubes (CNTs) are well-suited because of their unique properties; their small size, hollow center, large surface area and good electric conductivity. However, it has been shown that pristine carbon nanotubes have a low response for volatile organic compounds–our target analyte-therefore we attempted to improve this property of CNTs by templating pyrrole on CNTs. TEM, Raman spectroscopy, I-V characteristics and voltammetry were used to study the structural properties of CNTs/Polypyrrole. Polypyrrole is simple to prepare by oxidation of the monomer and its resistance is very sensitive to organic vapors, although much larger than that of CNTs. TEM of polypyrrole/CNT composites prepared from single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) show polypyrrole coated the CNTs successfully. There are significant changes in the range of diameters of nano tubes for SWCNTs from (7-10) nm to (8-35) nm and from (2-10) to (21-50) nm for MWCNTs. The composites were tested for the variation in their resistance upon exposure to a range of organic vapors (acetone methanol and chloroform). The sensing devices comprised simple two-terminal devices over which a layer of the composite was applied by drop-coating. We investigated the effect of the CNT: polypyrrole ratio on the sensor response, S=(R-R0)/R0 where R0 is the resistance in an air atmosphere and R is the resistance at steady-state after exposure to an air/analyte mixture. In general, bare CNTs show a rapid response time, but very low response (typically S<0.1) at room temperature. As the amount of polypyrrole in the composite is increased, S increases, the response time deteriorates. Interestingly, the response of the composites may even change sign as a function of target analyte concentration; this suggests that a simple mechanism based on swelling and its effect on the percolation behavior of CNTs in the polypyrrole matrix is insufficient to explain the data.

V S Filinov is a Professor of Joint Institute for High Temperatures of the Russian Academy of Sciences, Russia. He has published in many journals. His research interests are theoretical physics, plasma physics and thermodynamics.

The new numerical version of the Wigner approach to quantum mechanics for treatment of the strongly interacting electron-hole plasma has been developed for conditions, when there are no small physical parameters, and analytical approximations used in different kind of perturbation theories cannot be applied. The new path integral representation of the quantum Wigner function in the phase space has been developed for canonical ensemble. Explicit expression of the Wigner function has been obtained in linear and harmonic approximations. The new quantum Monte-Carlo method for calculations of average values of arbitrary quantum operators has been proposed. Monte Carlo calculations of the momentum distribution function for the electron-hole plasma has been carried out. Comparison with classical Maxwell–Boltzmann distribution shows the significant influence of quantum effects on the high energy asymptotics (‘tails’) of the momentum distribution functions, which resulted in appearance of the power-behaved decay instead of exponential one. Quantum effects can affect the shape of the particle kinetic energy distribution function, as the interaction of a particle with its surroundings restricts the volume of configuration space, which, due to the uncertainty relation, results in an increase in the volume of the momentum space, i.e., in a rise in the fraction of particles with higher momenta. Allowing for quantum effects is important in kinetic consideration of such phenomena as the transition of combustion into detonation, flame propagation, vibrational relaxation, and even thermonuclear fusion at high pressure and low temperatures. Quantum effects are also important in treatment of transport properties of the strongly interacting systems of many particles. The direct way to consider the influence of the quantum effects on the kinetic distribution functions is to use the Wigner formulation of quantum mechanics in phase space. The quantum Wigner function is similar to distribution function in classical statistics in phase space. Thereby, average values of arbitrary physical quantities can be calculated by formulas, similar to classical statistics.

The spin wave approach is used to describe the paramagnetic with pair dipole interaction of magnetic moments. It is based on the Holstein–Primakoff transformation of spin operators. Lattice Hamiltonian includes Zeeman energy and full dipolar energy with secular and non-secular terms, while the exchange energy is assumed to be negligible. The model describes the nuclear subsystem of paramagnetic insulator, e.g. solid H and O, 13C-enriched materials and electron shell system of rare earth salts where the exchange interaction vanishes due to the large distance between magnetic atoms. The 2D paramagnetic crystal is considered. It is placed into the uniform constant magnetic field which is orthogonal to the lattice plane. The magnetic saturation is considered as the ground state. All spins orient along field at the saturation and disorder occur because of thermodynamic fluctuations. The dipolar interaction causes the collective spin deviation at ultracold limit; the temperature must be <0.001 K for typical paramagnetics. In the current study, the thermal dependence of magnetization and specific heat were found taking into account the spin wave elastic scattering. The specific heat curve differs from the well-established Schottky law which realizes in the ideal paramagnetics without particle interaction. Nevertheless, the Schottky curve is confirmed for the temperatures >0.01 K and it may change in the ultracold region. Also, the spin wave approximation becomes applicable under the high magnetic fields. It requires the additional numerical or experimental studies.

Kirill Tsiberkin has completed his PhD from Perm State University (PSU). He is the Teaching Assistant of Theoretical Physics Department of PSU, Technician at the electronic manufacturer “Control Systems”, Perm, Russia and Executive Secretary of the PSU Physical Faculty Bulletin. He has published 12 papers in peer-reviewed journals (8 of them are indexed in WoS/Scopus) in areas of fluid dynamics, signal processing and magnetism.