Two-dimensional graphene-like Xenes as potential topological materials

Abstract

Since the discovery of quantum spin Hall (QSH) effect in graphene, searching for two-dimensional (2D) QSH materials with larger bulk gap has been an active field in the past decade. As cousins of graphene, the elemental graphene-like 2D materials (Xenes, X refers to group-IV, group-V, or group-VI elements) have been particularly interested in search of the QSH state as they share a similar honeycomb lattice with graphene. For those Xenes with heavier elements, theory predicted an extraordinarily large bulk gap suitable for room-temperature applications that have been experimentally verified in recent epitaxially grown bismuthene and stanene samples. We briefly review the progress in theoretical and experimental investigations of 2D Xenes as possible QSH topological materials.