Twisted bilayered graphenes at magic angles and Casimir interactions: correlation-driven effects

TL;DR

This paper explores how Casimir interactions can reveal electronic correlation effects and phase properties in twisted bilayer graphene at magic angles, linking quantum electronic states to measurable macroscopic forces.

Contribution

It demonstrates that Casimir forces and torques can be used to detect anisotropy and topological phases in magic angle twisted bilayer graphene, providing a new experimental probe.

Findings

Casimir torque probes anisotropy in nematic states

Repulsive Casimir force indicates topologically nontrivial phases

Electronic and optical response calculations support these effects

Abstract

Twisted bilayered graphenes at magic angles are systems housing long ranged periodicity of Moir\'e pattern together with short ranged periodicity associated with the individual graphenes. Such materials are a fertile ground for novel states largely driven by electronic correlations. Here we find that the ubiquitous Casimir force can serve as a platform for macroscopic manifestations of the quantum effects stemming from the magic angle bilayered graphenes properties and their phases determined by electronic correlations. By utilizing comprehensive calculations for the electronic and optical response, we find that Casimir torque can probe anisotropy from the Drude conductivities in nematic states, while repulsion in the Casimir force can help identify topologically nontrivial phases in magic angle twisted bilayered graphenes.