Coulomb drag in the quantum Hall $\nu = 1/2$ state: Role of disorder

TL;DR

This paper investigates Coulomb drag in the $ u=1/2$ quantum Hall state, revealing large resistivity enhancements due to magnetic field effects and analyzing disorder's impact on temperature dependence.

Contribution

It provides a detailed analysis of Coulomb drag at $ u=1/2$, highlighting the role of disorder and magnetic field in modifying resistivity and temperature scaling behaviors.

Findings

$ ho_D$ is significantly larger than in zero magnetic field.

Disorder reduces transresistivity compared to the clean system.

Temperature dependence shifts from $T^{4/3}$ to $T^2 \,\log T$ with disorder.

Abstract

We consider Coulomb drag between two layers of two-dimensional electron gases subject to a strong magnetic field, with the Landau level filling factor in each layer being 1/2. We find $\rho_D$ to be very large, as compared to the zero magnetic field case. We attribute this enhancement to the slow decay of density fluctuations in a strong magnetic field. For a clean system, the linear $q$-dependence of the longitudinal conductivity, characteristic of the $\nu=1/2$ state, leads a unique temperature dependence---$\rd \propto T^{4/3}$. Within a semiclassical approximation, disorder leads to a decrease of the transresistivity as compared with the clean case, and a temperature dependence of $T^2\log T$ at low temperatures.