Mesoscopic fluctuations of the Coulomb drag

TL;DR

This paper investigates mesoscopic fluctuations of Coulomb drag in two-dimensional electron gases, revealing that at low temperatures, fluctuations dominate the average, causing random sign and a temperature dependence of approximately 1/√T.

Contribution

It demonstrates that mesoscopic fluctuations can surpass the average Coulomb drag, leading to sign randomness and a specific temperature dependence in 2D electron gases.

Findings

Sample-to-sample fluctuations exceed the average at low temperatures.

The sign of Coulomb drag becomes random at low temperatures.

Temperature dependence of Coulomb drag saturates as 1/√T.

Abstract

We consider mesoscopic fluctuations of the Coulomb drag coefficient $\rho_D$ in the system of two separated two-dimensional electron gases. It is shown that at low temperatures sample to sample fluctuations of $\rho_D$ exceed its ensemble average. It means that in such a regime the sign of $\rho_D$ is random and the temperature dependence almost saturates $\rho_D \sim 1/\sqrt{T}$.