Plasmon and dielectric background inhomogeneity enhancement of Coulomb drag in graphene double-layer structures

TL;DR

This paper investigates how dielectric inhomogeneity and plasmon effects significantly enhance Coulomb drag in graphene double-layer structures across various temperatures and separations, revealing complex dependencies on inter-layer spacing.

Contribution

It demonstrates the impact of dielectric background inhomogeneity and plasmon-mediated screening on Coulomb drag, providing new insights into the behavior of graphene double layers.

Findings

Dielectric inhomogeneity significantly enhances drag resistivity.

Plasmon-mediated dynamical screening causes an upturn in drag at intermediate temperatures.

Drag resistivity scales approximately quadratically with inter-layer separation in certain regimes.

Abstract

The drag of massless fermions in graphene double-layer structures is investigated in a wide rage of temperatures and inter-layer separations. We show that the inhomogeneity of the dielectric background in such graphene structures for experimentally relevant parameters results in a significant enhancement of the drag resistivity. At intermediate temperatures the dynamical screening via plasmon-mediated drag enhances the drag resistivity and results in an upturn in its behavior at large inter-layer separations. In a range of inter-layer separations, corresponding to the strong-to-weak crossover coupling of graphene layers, we find that the drag resistivity decreases approximately quadratically with the inter-layer spacing. This dependence weakens with a decrease of the inter-layer spacing while for larger separations we recover the cubic (quartic) dependence at intermediate (low) temperatures.