Condensed Matter
We perform extended numerical simulation of the dynamics of dry friction, based on a model derived from the phenomenological description proposed by T. Baumberger et al.. In the case of small deviation from the steady sliding motion, the…
An ab initio approach to the calculation of excitonic effects in the optical absorption spectra of semiconductors and insulators is formulated. It starts from a quasiparticle bandstructure calculation and is based on the relevant…
A quantum field theory, consisting of the effective action of sound waves linearly coupled to a Chern-Simons term, is proposed to describe the dynamics of vortices in a superfluid film at the absolute zero of temperature.
We study an AFM Heisenberg S=2 quantum spin chain at T=0 with both interaction and on-site anisotropy, H = \sum_{i} {1/2}(S^{+}_{i}S^{-}_{i+1}+S^{-}_{i}S^{+}_{i+1}) +J^{z}S^{z}_{i}S^{z}_{i+1}+D(S^{z}_{i})^{2}. Contradictory scenarios exist…
We formulate a theory to the 2D Hubbard model in a framework free of finite size effect and numerical analytical continuation, yet containing the essential features of the 2D Hubbard model, i.e., the correct atomic limit for large…
Fractal structures appear in a vast range of physical systems. A literature survey including all experimental papers on fractals which appeared in the six Physical Review journals (A-E and Letters) during the 1990's shows that experimental…
A new technique for calculating the time-evolution, correlations and steady state spectra for nonlinear stochastic differential equations is presented. To illustrate the method, we consider examples involving cubic nonlinearities in an…
Microcavity inhomogeneous line widths are calculated numerically using a microscopic two dimensional model of the polariton interaction with quantum well disorder. The calculations show show that in most structures the line widths are…
We present a study of dynamical scaling and front motion in a one dimensional system that describes Rayleigh-Benard convection in a rotating cell. We use a model of three competing modes proposed by Busse and Heikes to which spatial…
A class of quasi two and three dimensional quantum lattice spin models with nearest and next nearest neighbour interactions is proposed. The basic idea of construction is to introduce interactions in an array of XXZ spin chains through…
We outline a path integral derivation of both the transverse force, the Berry phase, and friction for a vortex from the microscopic fermionic superfluid theory. The derivation manifests transparently the mutual independence of the Berry…
We present evidence suggesting that spin transport in the gapless phase of the S=1/2 XXZ model is ballistic rather than diffusive. We map the model onto a spinless fermion model whose charge stiffness determines the spin transport of the…
Using the bosonization method, we study the low temperature behavior of the Kondo effect in the Tomonaga-Luttinger liquid and clearly show that the power law temperature dependence of the impurity susceptibility is completely determined by…
A method based on Monte Carlo sampling of the probability flows projected onto the subspace of one or more slow variables is proposed for investigation of dynamic and static properties of lattice spin systems. We illustrate the method by…
A formula suitable for a quantitative evaluation of the tunneling effect in a ferromagnetic particle is derived with the help of the instanton method. The tunneling between n-th degenerate states of neighboring wells is dominated by a…
A strongly correlated electron system with controlled hopping, in the line of the recently proposed generalized Hubbard models as candidates for high T_c-superconductors, is considered. The model along with a whole class of such systems are…
We study the t-J model on a ladder by using slave-fermion-CP^1 formalism which is quite useful for study of lightly-doped high-T_c cuprates. By integrating half of spin variables, we obtain a low-energy effective field theory whose spin…
We investigate the problem of forces on moving vortex in a superfluid or superconductor. The main purpose is to locate the source which leads to the contradictory results in the literature. We establish the connection between this problem…
The interference of the directly emitted photoelectron wave and the wave scattered coherently by neighboring atoms gives holographic fringes in the photoelectron emission intensity $I(\hat{\bf R})$. In the electron emission holography…
We report an inelastic neutron scattering study of antiferromagnetic spin dynamics in the Haldane chain compound Ni(C2H8N2)2NO2ClO4 (NENP) under external hydrostatic pressure P = 2.5 GPa. At ambient pressure, the magnetic excitations in…