Quantum Spin Hall Effect in Magnetic Graphene

TL;DR

This paper demonstrates the realization of quantum spin Hall states in magnetic graphene at zero external magnetic field through proximity effects with an antiferromagnetic layer, enabling potential spintronic applications.

Contribution

It reports the experimental detection of spin-polarized helical edge states in magnetic graphene induced by proximity effects without external magnetic fields.

Findings

Detection of quantum spin Hall states at zero magnetic field

Observation of a large anomalous Hall effect up to room temperature

Coexistence of topological edge states and magnetism in graphene

Abstract

A promising approach to attain long-distance coherent spin propagation is accessing topological spin-polarized edge states in graphene. Achieving this without external magnetic fields necessitates engineering graphene band structure, obtainable through proximity effects in van der Waals heterostructures. In particular, proximity-induced staggered potentials and spin-orbit coupling are expected to form a topological bulk gap in graphene with gapless helical edge states that are robust against disorder. In this work, we detect the spin-polarized helical edge transport in graphene at zero external magnetic field, allowed by the proximity of an interlayer antiferromagnet, CrPS$_4$. We show the coexistence of the quantum spin Hall (QSH) states and magnetism in graphene, where the induced spin-orbit and exchange couplings also give rise to a large anomalous Hall (AH) effect. The detection of the QSH states at zero external magnetic field, together with the AH signal that persists up to room temperature, opens the route for practical applications of magnetic graphene in quantum spintronic circuitries.