Coulomb drag by motion of a monolayer polar crystal through graphene nanoconstriction

TL;DR

This paper predicts a Coulomb drag effect caused by a moving polar crystal layer between graphene sheets, leading to a measurable current and nonlinear Hall effects, with implications for understanding electron interactions and material dynamics.

Contribution

It introduces a novel theoretical model of Coulomb drag induced by a moving polar crystal layer in graphene, highlighting the effects of intervalley scattering and pseudospin interactions.

Findings

Drag effect appears above a threshold doping level.

Nonlinear Hall effect observed due to pseudospin interactions.

Drag influences the dynamic viscosity of the crystalline layer.

Abstract

We theoretically predict that the motion of a polar crystalline layer between two graphene planes exerts Coulomb drag on electrons in graphene, inducing a DC drag current. The physical mechanism underlying this drag arises from intervalley scattering of charge carriers in graphene caused by the time-dependent potential of the moving crystalline layer. This drag effect manifests above a finite threshold doping of the graphene layers, which is determined by the lattice structure and the relative orientation of the crystalline layer with respect to the graphene lattice. Additionally, the drag current exhibits a nonlinear Hall effect due to the interplay between the induced nonequilibrium pseudospin and the intrinsic pseudospin-orbit coupling in graphene. In turn, the drag exerted on electrons in graphene produces a backaction on the crystalline layer, which can be described as an increase in its dynamic viscosity.