凝聚态物理
The low-energy density of states (DOS) of disordered 2D d-wave superconductors is extremely sensitive to details of both the disorder model and the electronic band structure. Using diagrammatic methods and numerical solutions of the…
The fundamental question of how Bose-Einstein condensates tunnel into a barrier is addressed. The cubic nonlinear Schrodinger equation with a finite square well potential, which models a Bose-Einstein condensate in a quasi-one-dimensional…
Chemical bonding and electronic structure of MgB2, a boron-based newly discovered superconductor, is studied using self-consistent band structure techniques. Analysis of the transformation of the band structure for the hypothetical series…
We present a theory of electron, electromagnetic, and elastic wave propagation in systems consisting of non-overlapping scatterers in a host medium. The theory provides a framework for a unified description of wave propagation in…
We present the results on the soliton excitations in carbon nanotubes (CNT) using Brenner's many-body potential. Our numerical simulations demonstrate high soliton stability in (10,10) CNT. The interactions of solitons and solitary…
We consider the bosonic dimer representation for Generalized Shastry-Sutherland models that have the same symmetries as the original Shastry-Sutherland model and preserve the exact dimer eigenstate. Various phases with differing types of…
We present a study of nonlinear localized excitations called discrete breathers in a superconducting array. These localized solutions were recently observed in Josephson-junction ladder arrays by two different experimental groups. We review…
We present the results of molecular dynamics simulations of the extended simple point charge (SPC/E) model of water to investigate thethermodynamic and dynamic properties of stretched and supercooled water. We locate the liquid-gas…
Thermodynamics in the vicinity of a critical endpoint with nonclassical exponents $\alpha$, $\beta$, $\gamma$, $\delta$, $...$ is analyzed in terms of density variables (mole fractions, magnetizations, etc.). The shapes of the isothermal…
Antiferromagnetic coupling between ferromagnetic layers has been observed for the first time in all-semiconductor superlattice structure EuS/PbS(001), by neutron scattering and magnetization measurements. Spin-dependent superlattice band…
Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser-excitation. The surface and bulk components of the…
We study the dynamic structure factor $S(\vec{q},\omega)$ of superfluid 4He at zero temperature in the roton momentum region and beyond using field-theoretical Green's function techniques. We start from the Gavoret-Nozi\`{e}res two-particle…
We propose a phenomenological field theoretical approach to the chemical etching of a disordered-solid. The theory is based on a recently proposed dynamical etching model. Through the introduction of a set of Langevin equations for the…
For the first time, an experimental determination of the single-particle mean kinetic energies for 3He along the T=2.00 K isotherm in the dense liquid and in the solid hcp and bcc phases is reported. Deep Inelastic Neutron Scattering…
The Josephson oscillations between condensates in a double-well trap are known theoretically to be strongly effected by the mean field interaction in dilute atomic gases. The most important effect is that the amplitude of oscillation in the…
What is the microscopic interaction responsible for high temperature superconductivity (HTSC)? Here data on temporal relaxation of Tc and the room temperature conductivity in YBa2Cu3O(6+x) after abrupt alteration by light pulses or pressure…
The electron tunneling in half metallic manganite tunnel junctions is studied by using a quantum mechanically treated double exchange model. We show that the stimulation of spin excitations, caused by the strong Hund's coupling between the…
We analyze the propagation of activity in a system of mobile automata. A number r L^d of elements move as random walkers on a lattice of dimension d, while with a small probability p they can jump to any empty site in the system. We show…
We study the two-dimensional, disordered, attractive Hubbard model by the projector quantum Monte Carlo method and Bogoliubov - de Gennes mean-field theory. Our results for the ground state show the appearance of a new phase with charge…
The one-dimensional optical polaron is treated on the basis of the perturbation theory in the weak coupling limit. A special matrix diagrammatic technique is developed. It is shown how to evaluate all terms of the perturbation theory for…