Two-dimensional spin-valley-coupled Dirac semimetals in functionalized SbAs monolayers

TL;DR

This paper predicts that functionalized SbAs monolayers can host spin-valley-coupled Dirac semimetals with unique spin and valley properties, useful for spintronics and valleytronics, based on ab initio calculations.

Contribution

It introduces a new class of spin-valley-coupled Dirac semimetals in SbAs monolayers with giant SOC-induced spin-splitting and tunable topological states.

Findings

Dirac cones with giant spin-splitting in SbAs MLs

Observation of Dirac spin-valley Hall effect

Emergence of svc-DSM at topological phase boundary

Abstract

In the presence of spin-orbit coupling (SOC), achieving both spin and valley polarized Dirac state is significant to promote the fantastic integration of Dirac physics, spintronics and valleytronics. Based on ab initio calculations, here we demonstrate that a class of spin-valley-coupled Dirac semimetals (svc-DSMs) in the functionalized SbAs monolayers (MLs) can host such desired state. Distinguished from the graphene-like 2D Dirac materials, the Dirac cones in svc-DSMs hold giant spin-splitting induced by strong SOC under inversion symmetry breaking. In the 2.3% strained SbAsH2 ML, the Dirac fermions in inequivalent valleys have opposite Berry curvature and spin moment, giving rise to Dirac spin-valley Hall effect with constant spin Hall conductivity as well as massless and dissipationless transport. Topological analysis reveals that the svc-DSM emerges at the boundary between trivial and 2D topological insulators, which provides a promising platform for realizing the flexible and controllable tuning among different quantum states.