Time-Reversal Even Charge Hall Effect from Twisted Interface Coupling

TL;DR

This paper demonstrates a novel time-reversal even charge Hall effect in twisted layered 2D materials, enabled by interfacial coupling and chiral stacking, revealing new layer-dependent Hall physics and potential for layertronics.

Contribution

It introduces a new mechanism for a time-reversal even charge Hall effect via twisted interface coupling, expanding understanding of Hall phenomena in chiral layered structures.

Findings

Giant Hall ratios observed in twisted bilayer graphene and TMDs.

Hall effect can be switched on and off with gate voltage.

Effect relies on band geometric quantity, momentum-space vorticity.

Abstract

Under time-reversal symmetry, a linear charge Hall response is usually deemed to be forbidden by the Onsager relation. In this work, we discover a scenario for realizing a time-reversal even linear charge Hall effect in a non-isolated two-dimensional crystal allowed by time reversal symmetry. The restriction by Onsager relation is lifted by interfacial coupling with an adjacent layer, where the overall chiral symmetry requirement is fulfilled by a twisted stacking. We reveal the underlying band geometric quantity as the momentum-space vorticity of layer current. The effect is demonstrated in twisted bilayer graphene and twisted homobilayer transition metal dichalcogenides with a wide range of twist angles, which exhibit giant Hall ratios under experimentally practical conditions, with gate voltage controlled on-off switch. This work reveals intriguing Hall physics in chiral structures, and opens up a research direction of layertronics that exploits the quantum nature of layer degree of freedom to uncover exciting effects.