Coulomb Drag as a Probe of the Nature of Compressible States in a Magnetic Field

TL;DR

This paper investigates Coulomb drag in quantum Hall systems to understand the nature of compressible states, revealing distinct temperature dependencies and the effects of disorder and screening on electron interactions.

Contribution

It provides new insights into the temperature dependence of Coulomb drag at different Landau levels and discusses the roles of disorder, localization, and screening in these phenomena.

Findings

At rac{3}{2}, drag shows T^{4/3} dependence indicating metallic behavior.

Higher Landau levels exhibit anomalous drag growth with decreasing temperature.

Crossover to normal drag at high fields is attributed to screening of disorder.

Abstract

Magneto-drag reveals the nature of compressible states and the underlying interplay of disorder and interactions. At \nu=3/2 a clear T^{4/3} dependence is observed, which signifies the metallic nature of the N=0 Landau level. In contrast, drag in higher Landau levels reveals an additional contribution, which anomalously grows with decreasing T before turning to zero following a thermal activation law. The anomalous drag is discussed in terms of electron-hole asymmetry arising from disorder and localization, and the crossover to normal drag at high fields as due to screening of disorder.