Semiclassical theory of electron drag in strong magnetic fields

TL;DR

This paper develops a semiclassical model explaining electron drag phenomena in strong magnetic fields, including sign reversal and temperature behavior, aligning with recent experimental observations.

Contribution

It introduces a new semiclassical framework that clarifies the qualitative features of anomalous electron drag, emphasizing the role of dispersion curvature and localization effects.

Findings

Sign reversal of drag at mismatched densities explained

Sign of drag linked to dispersion curvature

Localization influences low-temperature activation behavior

Abstract

We present a semiclassical theory for electron drag between two parallel two-dimensional electron systems in a strong magnetic field, which provides a transparent picture of the most salient qualitative features of anomalous drag phenomena observed in recent experiments, especially the striking sign reversal of drag at mismatched densities. The sign of the drag is determined by the curvature of the effective dispersion relation obeyed by the drift motion of the electrons in a smooth disorder potential. Localization plays a role in explaining activated low temperature behavior, but is not crucial for anomalous drag per se.