Control of electron-electron interaction in graphene by proximity screening

TL;DR

This paper demonstrates how proximity to metallic gates can effectively control electron-electron interactions in graphene, with potential implications for tuning many-body phenomena in 2D materials.

Contribution

It provides experimental and theoretical insights into proximity screening effects on electron interactions in graphene using atomically-thin dielectrics and metallic gates.

Findings

Screening effects become significant at dielectric thicknesses of a few nanometers.

Measured electron scattering rates align with theoretical predictions.

Proximity screening can modulate electron viscosity and umklapp scattering in graphene.

Abstract

Electron-electron interactions play a critical role in many condensed matter phenomena, and it is tempting to find a way to control them by changing the interactions' strength. One possible approach is to place a studied system in proximity of a metal, which induces additional screening and hence suppresses electron interactions. Here, using devices with atomically-thin gate dielectrics and atomically-flat metallic gates, we measure the electron-electron scattering length in graphene and report qualitative deviations from the standard behavior. The changes induced by screening become important only at gate dielectric thicknesses of a few nm, much smaller than a typical separation between electrons. Our theoretical analysis agrees well with the scattering rates extracted from measurements of electron viscosity in monolayer graphene and of umklapp electron-electron scattering in graphene superlattices. The results provide a guidance for future attempts to achieve proximity screening of many-body phenomena in two-dimensional systems.