Large and Controllable Spin-Valley Splitting in Two-Dimensional WS2/h-VN Heterostructure

TL;DR

This study demonstrates large, controllable spin-valley splitting in a 2D WS2/h-VN heterostructure, enabling potential applications in valleytronics through first-principles calculations and strain tuning.

Contribution

It introduces a novel 2D heterostructure with tunable large spin and valley splitting, advancing valleytronics device design.

Findings

Spin splitting of 627 meV at K valley

Valley splitting of 376 meV in the valence band

Maximum spin and valley splitting of 654 and 412 meV

Abstract

Inspired by the profound physical connotations and potential application prospects of the valleytronics, we design a two-dimensional (2D) WS2/h-VN magnetic van der Waals (vdW) heterostructure and study the control of valley degree of freedom through the first-principles calculations. A considerable spin splitting of 627 meV is obtained at the K valley, accompanied with a strong suppression of that at the K' valley. An intrinsic large valley splitting of 376 meV is generated in the valence band, which corresponds to an effective Zeeman magnetic field of 2703 T. Besides of the valence band, the conduction band of WS2 possesses a remarkable spin splitting also, and valley labelled dark exciton states are present at the K' valley. The strengths of spin and valley splitting relied on the interfacial orbital hybridization are further tuned continually by the in-plane strain and interlayer spacing. Maximum spin and valley splitting of 654 and 412 meV are finally achieved, respectively, and the effective Zeeman magnetic field can be enhanced to 2989T with a -3 % strain. Time-reversal symmetry breaking and the sizable Berry curvature in the heterostructure lead to a prominent anomalous Hall conductivity at the K and K' valleys. Based on these finding, a prototype filter device for both the valley and spin is proposed.