arXiv subjects
Publications and source records attributed to D. E. Khmelnitskii.
The two-parameter renormalization group flow diagramme is used for obtaining the magnetic field dependence of localisation length Lc(B) for charged particles in 2D random potential at low disorder and weak magnetic fields B. The result reproduces the periodic singularities of Lc(B).
We study thermal transport in a one-dimensional quantum wire, connected to reservoirs. Despite of the absence of electron backscattering, interactions in the wire strongly influence thermal transport. Electrons propagate with unitary transmission through the wire and electric conductance is not affected. Energy, however, is carried by bosonic excitations (plasmons) which suffer from scattering even on scales much larger than the Fermi wavelength. If the electron density varies randomly, plasmons are localized and {\em charge-energy separation} occurs. We also discuss the effect of plasmon-plasmon interaction using Levinson's theory of nonlocal heat transport.
We calculate the energy level statistics in a two-dimensional disc with diffusive boundary scattering by the means of the recently proposed ballistic nonlinear sigma-model.
The free energy of the Coulomb Gap problem is expanded as a set of Feynman diagrams, using the standard diagrammatic methods of perturbation theory. The gap in the one-particle density of states due to long-ranged interactions corresponds to a renormalization of the two-point vertex function. By collecting the leading order logarithmic corrections we have derived the standard result for the density of states in the critical dimension, d=1. This method, which is shown to be identical to the approach of Thouless, Anderson and Palmer to spin glasses, allows us to derive the strong-disorder behaviour of the density of states. The use of the renormalization group allows this derivation to be extended to all disorders, and the use of an epsilon-expansion allows the method to be extended to d=2 and d=3. We speculate that the renormalization group equations can also be derived diagrammatically, allowing a simple derivation of the crossover behaviour observed in the case of weak disorder.
We use optimal fluctuation method for a new ballistic $σ$-model to study the long time dispersion of conductance $G(t)$ of a mesoscopic sample. In the long time limit the conductance of a $d$-dimensional sample decays as $\exp (-A \ln^d t ) $. At shorter times the new results match those in our previous paper. It is found that at very long times the diffraction effects are important and the ballistic treatment is not valid. We also suggest a physical picture of trapping.
We suggest an effective field theory for disorderd conductors, which describes quantum kinetics of ballistically propagating electrons. This theory contains non-linear $σ$-model \cite{Efetov} as its long wave limit.