Electric-field switchable chirality in rhombohedral graphene Chern insulators stabilized by tungsten diselenide

TL;DR

This paper demonstrates electrically switchable chirality in rhombohedral graphene-based Chern insulators by inducing topological phase transitions, enabling control over edge current direction for potential topological electronic applications.

Contribution

It introduces a method to reversibly switch the Chern number and chirality in rhombohedral multilayer graphene Chern insulators using moire superlattices and displacement fields.

Findings

Chern number can be tuned from -1, 1 to 2 via topological phase transitions.

Integration of tungsten diselenide stabilizes Chern insulators with quantized Hall resistance.

Chirality switching is achieved by applying displacement fields, enabling control over edge current direction.

Abstract

Chern insulators host topologically protected chiral edge currents with quantized conductance characterized by their Chern number. Switching the chirality of a Chern insulator, namely, the direction of the edge current, is highly challenging due to topologically forbidden backscattering but is of considerable importance for the design of topological devices. Nevertheless, this can be achieved by reversing the sign of the Chern number through a topological phase transition. Here, we report electrically switchable chirality in rhombohedral multilayer graphene-based Chern insulators. By introducing moire superlattices in rhombohedral heptalayer graphene, we observed a cascade of topological phase transitions at quarter electron filling of a moire band with the Chern number tunable from -1, 1 to 2. Furthermore, integrating monolayer tungsten diselenide at the moireless interface of rhombohedral decalayer graphene/h-BN superlattices stabilizes the Chern insulators, enabling quantized anomalous Hall resistance of h/2e^2. Remarkably, the Chern number can be switched from -1 to 2 using displacement fields. Our work establishes rhombohedral multilayer graphene moire superlattices as a versatile platform for topological engineering, with switchable chirality offering significant promise for integrating chiral edge currents into topological electronic circuits.