Intrinsic spin Hall effect in monolayers of group-VI dichalcogenides: A first-principles study

TL;DR

This study uses first-principles calculations to explore the intrinsic spin Hall effect in monolayer group-VI dichalcogenides, revealing large spin Hall conductivities and potential for valleytronics and spintronics applications.

Contribution

It provides the first detailed first-principles analysis of the intrinsic spin Hall effect in monolayer MX2 dichalcogenides, highlighting their suitability for valleytronics and spintronics.

Findings

Large intrinsic spin Hall conductivity in p-doped monolayers.

Significant difference in spin Hall conductivity between monolayers and bulk.

Monolayers exhibit stronger spin Hall effects due to inversion symmetry breaking.

Abstract

Using first-principles calculations within density functional theory, we investigate the intrinsic spin Hall effect in monolayers of group-VI transition-metal dichalcogenides MX2 (M = Mo, W and X = S, Se). MX2 monolayers are direct band-gap semiconductors with two degenerate valleys located at the corners of the hexagonal Brillouin zone. Because of the inversion symmetry breaking and the strong spin-orbit coupling, charge carriers in opposite valleys carry opposite Berry curvature and spin moment, giving rise to both a valley- and a spin-Hall effect. The intrinsic spin Hall conductivity (ISHC) in p-doped samples is found to be much larger than the ISHC in n-doped samples due to the large spin-splitting at the valence band maximum. We also show that the ISHC in inversion-symmetric bulk dichalcogenides is an order of magnitude smaller compared to monolayers. Our result demonstrates monolayer dichalcogenides as an ideal platform for the integration of valleytronics and spintronics.