Coulomb drag between two graphene layers at different temperatures

TL;DR

This paper theoretically investigates Coulomb drag between two graphene layers with different temperatures, revealing significant deviations from standard behavior and a strong dependence on temperature difference and interlayer separation.

Contribution

It introduces a theoretical model for Coulomb drag in graphene with temperature imbalance, highlighting new temperature-dependent behaviors and asymmetries.

Findings

Drag resistivity varies as T/d^5 when one layer is much hotter.

Drag magnitude is larger when the active layer has higher temperature.

Deviation from quadratic temperature dependence in the presence of temperature difference.

Abstract

We theoretically study the Coulomb drag in graphene when there is a temperature difference between the layers. Within the degenerate limit for equal layer densities, we find that this can lead to significant deviations from the usual quadratic temperature dependence of the drag resistivity. The exact behavior depends strongly on the phase space available for intraband scattering, and is not symmetrical when the temperatures of the layers are interchanged. In particular, when one layer is at a much higher temperature $T$ than the other, the drag resistivity behaves as $\rho_D\sim T/d^5$, where $d$ is the interlayer separation. The magnitude of the drag in this limit is always larger when the active layer is at the higher temperature.