Coulomb drag between massless and massive fermions

TL;DR

This paper provides a theoretical analysis of Coulomb drag between massless and massive fermions in a double-layer system, offering analytical formulas and exploring dependencies on temperature, density, and interlayer separation.

Contribution

It introduces a detailed theoretical framework for Coulomb drag between massless and massive fermions, including analytical expressions and comparative analysis with similar systems.

Findings

Density dependence differs at small interlayer separation.

Large separation limit shows similar density dependence across systems.

Double-layer graphene-bilayer and monolayer structures exhibit similar drag behavior.

Abstract

We theoretically investigate the frictional drag induced by the Coulomb interaction between spa- tially separated massless and massive fermions at low temperatures. As a model system, we use a double-layer structure composed of a two-dimensional electron gas (2DEG) and a n-doped graphene layer. We analyze this system numerically and also present analytical formulae for the drag re- sistivity in the limit of large and small interlayer separation. Both, the temperature and density dependence are investigated and compared to 2DEG-2DEG and graphene-graphene double-layer structures. Whereas the density dependence of the transresistivity for small interlayer separation differs already in the leading order for each of those three structures, we find the leading order con- tribution of density dependence in the large interlayer separation limit to exhibit the same density dependence in each case. In order to distinguish between the different systems in the large interlayer separation limit, we also investigate the subleading contribution to the transresistivity. Furthermore, we study the Coulomb drag in a double-layer structure consisting of n-doped bilayer and monolayer graphene, which we find to possess the same qualitative behavior as the 2DEG-graphene system.