Time-reversal even charge hall effect from twisted interface coupling

A linear Hall response in isolated systems with time reversal symmetry is forbidden by Onsager relations. Here the authors show that this restriction is lifted by interlayer hopping in twisted bilayers, leading to a linear charge Hall effect under time reversal symmetry. 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.

Automated summary

The authors find that interlayer hopping in twisted bilayers allows for a linear charge Hall effect under time reversal symmetry, which is typically forbidden by the Onsager relation. This effect is achieved through interfacial coupling and a twisted stacking, which fulfills the overall chiral symmetry requirement. The research demonstrates this effect in twisted bilayer graphene and twisted homobilayer transition metal dichalcogenides, showing giant Hall ratios under experimentally practical conditions and gate voltage control.