Generation and Enhancement of Valley Polarization in Monolayer Chromium Dichalcogenides.

Valleytronic properties of monolayer transition metal dichalcogenides have attracted extensive attention owing to its intriguing fundamental physics and potential application for future electronics. Here, we investigate the spin-valley coupling and valley polarization of monolayer chromium dichalcogenides induced by the magnetic proximity effect using first-principle calculations. It is found that monolayer CrX2 (X = S, Se, and Te) have inherent spin-valley coupling and a sizable Zeeman-type spin splitting near the maximum of valance band. The valley-contrasting characteristics are further clarified by the Berry curvature, which induces a novel spin/valley Hall effect. Finally, CrSe2/MnO2 heterostructure is proposed to introduce valley polarization via a magnetic proximity effect. A primitive valley splitting of 31 meV is induced at the maximum of valance band, corresponding to a Zeeman field of 185 T. More interestingly, the valley splitting could be effectively enhanced over a wide range by an electric field or out-of-plane strain. [ABSTRACT FROM AUTHOR]