Strange metallicity of moir\'e twisted bilayer graphene

TL;DR

This paper investigates the linear-in-temperature resistivity observed in moiré twisted bilayer graphene, analyzing whether acoustic phonons can explain this 'strange metal' behavior through detailed theoretical comparison with recent experimental data.

Contribution

It provides a theoretical analysis of phonon scattering as a possible explanation for the strange metallicity in tBLG, comparing predictions with new experimental results.

Findings

Resistive scattering by acoustic phonons can partly explain the linear-in-temperature resistivity.

Some aspects of the experimental data are inconsistent with pure phonon scattering.

The work highlights the need for additional mechanisms to fully account for the observed behavior.

Abstract

Recent measurements in several different laboratories report the observation of an approximately linear-in-temperature resistivity with a large twist-angle-dependent slope (or temperature coefficient) in moir\'e twisted bilayer graphene (tBLG) down to a few K and sometimes to much lower temperatures. In this note, we theoretically discuss this `strange metal' linear-in-temperature transport behavior from the perspective of resistive scattering by acoustic phonons, emphasizing the aspects of the transport data, which are and which are not consistent with the phonon scattering mechanism. Extensive theoretical comparison with a new experiment [A. Jaoui et al., Nature Physics 18, 633 (2022)] is the central new aspect of this work.