Isovalent alloying assisted anomalous valley Hall effect in hexagonal antiferromagnetic monolayer

TL;DR

This paper proposes a method using isovalent alloying to induce spin splitting in hexagonal antiferromagnetic monolayers, enabling anomalous valley Hall effect for valleytronic applications, verified through first-principles calculations.

Contribution

It introduces a novel alloying strategy to break $PT$ symmetry and achieve AVHE in AFM monolayers, supported by first-principles verification.

Findings

Alloying breaks $PT$ symmetry, inducing spin splitting.

Strain enhances valley splitting and preserves AFM order.

CrMoC₂S₆ monolayer exhibits spontaneous valley polarization.

Abstract

Exploring combination of antiferromagnetic (AFM) spintronics and anomalous valley Hall effect (AVHE) is one of the most important questions for valleytronic applications. The key to address this issue is to achieve spin splitting around the valleys in AFM systems. Here, we propose a possible way for achieving AVHE in hexagonal AFM monolayer, which involves the isovalent alloying. This can break the combined symmetry ($PT$ symmetry) of spatial inversion ($P$) and time reversal ($T$), giving rise to spin splitting. More specifically, the large spin splitting around the Fermi energy level owes to $d$ orbital mismatch among these different transition metal ions. Based on first-principles calculations, the proposed way can be verified in out-of-plane AFM $\mathrm{CrMoC_2S_6}$ monolayer, which possesses spontaneous valley polarization and spitting splitting, providing possibility to realize AVHE. It is also proved that tensile strain can strengthen the valley splitting and maintain the out-of-plane AFM ordering. Our works provide an experimentally feasible way for developing AFM valleytronic devices.