Giant elastoresistance in magic-angle twisted bilayer graphene

TL;DR

This study reveals giant elastoresistance in magic-angle twisted bilayer graphene, showing highly sensitive electronic responses to uniaxial strain near the magic angle, which can probe correlated electronic phases.

Contribution

It demonstrates that uniaxial strain induces extremely large elastoresistance in twisted bilayer graphene, providing a new method to explore correlated and topological phases.

Findings

Elastoresistance exceeds 100 times that of conventional metals.

Elastoresistance depends on band filling and temperature.

Divergence of elastoresistance suggests nematic fluctuations.

Abstract

Strongly correlated and topological phases in moir\'e materials are exquisitely sensitive to lattice geometry at both atomic and superlattice length scales. Twist angle, pressure, and strain directly modify the lattice, and thus act as highly effective tuning parameters. Here we examine electrical transport in twisted bilayer graphene subjected to continuous uniaxial strain. Near the magic angle ($\approx 1.1^{\circ}$), devices exhibit a pronounced elastoresistance that depends on band filling and temperature, with a gauge factor more than two orders of magnitude larger than that of conventional metals. In selected doping regimes the elastoresistance exhibits a Curie-Weiss-like temperature divergence. We discuss possible microscopic origins, including nematic fluctuations and enhanced electronic entropy from fluctuating isospin moments. Our work establishes uniaxial strain as a versatile probe of correlated physics in a moir\'e material.