Coulomb drag in graphene - boron nitride heterostructures: the effect of virtual phonon exchange

TL;DR

This paper investigates how virtual phonon exchange via the boron nitride substrate significantly alters Coulomb drag resistivity in graphene heterostructures at temperatures above 150 K, highlighting the substrate's anisotropic structure.

Contribution

It introduces the effect of virtual substrate phonon exchange into the Coulomb drag model for graphene-boron nitride heterostructures, showing substantial impact on drag resistivity predictions.

Findings

Drag resistivity is significantly modified at temperatures above 150 K.

The anisotropic structure of boron nitride influences the electron-electron interaction.

Virtual phonon exchange plays an important role in the drag effect.

Abstract

For a system of two spatially separated monoatomic graphene layers encapsulated in hexagonal boron nitride, we consider the drag effect between charge carriers in the Fermi liquid regime. Commonly, the phenomenon is described in terms of an interlayer Coulomb interaction. We show that if an additional electron - electron interaction via exchange of virtual substrate phonons is included in the model, the predicted drag resistivity is modified considerably at temperatures above 150 K. The anisotropic crystal structure of boron nitride, with strong intralayer and comparatively weak interlayer bonds, is found to play an important role in this effect.