Semiclassical description of the dynamics and pinning in charge-density waves.

Abstract

I derive equations to predict the evolution of the experimentally controllable macroscopic variables, e.g., total current and voltage drop, relevant in describing charge-density-wave conduction. The equations are obtained from a ``semiclassical'' approximation with expansion parameter 1/\ensuremath{\lambda}, where \ensuremath{\lambda}==${\mathit{VMv}}_{\mathit{f}}$${\mathit{k}}_{\mathit{f}}$/4\ensuremath{\pi}${\mathit{p}}_{\mathit{f}}$${\mathit{a}}_{\mathrm{\ensuremath{\perp}}}^{\mathit{d}\mathrm{\ensuremath{-}}1}$. The Fr\"ohlich mass, M, Fermi velocity, Fermi momentum, and Fermi wave number (${\mathit{v}}_{\mathit{f}}$, ${\mathit{p}}_{\mathit{f}}$, and ${\mathit{k}}_{\mathit{f}}$), as well as the transverse chain ``area'' ${\mathit{a}}_{\mathrm{\ensuremath{\perp}}}^{\mathit{d}\mathrm{\ensuremath{-}}1}$, are all independent of the volume V. Therefore, the equations found are exact in the thermodynamic limit. While the equations have the appearance of classical Langevin equations, there appear coefficients that depend on microscopic correlations. I study this dependence qualitatively using the Feynman-Vernon method. An exact action depending only on the phase at the impurity sites is derived and reduced to a single-site problem using a self-consistent mean-field theory.