Coulomb drag in metallic twisted bilayer graphene

TL;DR

This paper theoretically investigates Coulomb drag in metallic twisted bilayer graphene, revealing unique maxima and multiple peaks in drag resistivity related to twist angle variations and many-body interactions.

Contribution

It introduces a novel Coulomb drag setup in metallic TBG and analyzes how twist angle variations influence drag resistivity, highlighting new many-body effects.

Findings

Drag resistivity peaks at the crossover from degenerate to nondegenerate regimes.

Multiple peaks in drag resistivity occur when twist angles differ.

Behavior linked to the twist angle dependence of the rectification function.

Abstract

Strongly correlated phases in twisted bilayer graphene (TBG) typically arise as transitions from a state in which the system behaves as a normal metal. In such metallic regime, electron-electron interactions usually only play a subleading role in transport measurements, compared to the dominant scattering mechanism. Here, we propose and theoretically study an exception to this based on a Coulomb drag setup between two metallic TBG, separated so that they only couple through many-body interactions. We find that by solely varying the twist angle equally in both TBG, the drag resistivity exhibits a unique maximum as the system crossovers from a degenerate to a nondegenerate regime. When the twist angles in each TBG differ, we find an anomalous drag resistivity characterized by the appearance of multiple peaks. We show that this behavior can be related to the dependence of the rectification function on the twist angle.