Strong interminivalley scattering in twisted bilayer graphene revealed by high-temperature magnetooscillations

TL;DR

This study uncovers strong interminivalley scattering in twisted bilayer graphene through high-temperature magnetooscillations, revealing insights into electron transport and collision rates influenced by the superlattice structure.

Contribution

It provides the first direct evidence of strong interminivalley scattering in TBG using high-temperature magnetooscillations, and estimates electron-electron collision rates.

Findings

Interminivalley scattering in TBG is strong and comparable to intraminivalley scattering.

High-temperature magnetooscillations originate from charge carrier scattering between minivalleys.

Electron-electron collision rate in TBG exceeds that of monolayer graphene.

Abstract

Twisted bilayer graphene (TBG) provides an example of a system in which the interplay of interlayer interactions and superlattice structure impacts electron transport in a variety of non-trivial ways and gives rise to a plethora of interesting effects. Understanding the mechanisms of electron scattering in TBG has, however, proven challenging, raising many questions about the origins of resistivity in this system. Here we show that TBG exhibits high-temperature magnetooscillations originating from the scattering of charge carriers between TBG minivalleys. The amplitude of these oscillations reveals that interminivalley scattering is strong, and its characteristic time scale is comparable to that of its intraminivalley counterpart. Furthermore, by exploring the temperature dependence of these oscillations, we estimate the electron-electron collision rate in TBG and find that it exceeds that of monolayer graphene. Our study demonstrates the consequences of the relatively small size of the superlattice Brillouin zone and Fermi velocity reduction on lateral transport in TBG.