We propose that a half semiconducting state can exist in trigonal-prismatic transition metal dichalcogenide (TMDC) monolayers of d1 configuration. In that state both electrons and holes are spin polarized and share the same spin channel. On the basis of hybrid density functional theory, we predict in particular that VS2 monolayers are half semiconductors with a direct band gap. Moreover, we find that the conduction electron spin orientation of VS2 switches under moderate strain. Our predictions thus open up intriguing possibilities for applications of VS2 in spintronics and optoelectronics. Our analysis of trigonal-prismatic group-V MX2 (M=V, Nb, Ta; X=S, Se, Te) monolayers reveals a broad diversity of electronic states that can be understood qualitatively in terms of localization of d electrons.
@article{arxiv.1501.00760,
title = {Prediction of switchable half semiconductor in d$^{1}$ transition metal dichalcogenide monolayers},
author = {Peng-Ru Huang and Yao He and Hridis K. Pal and Markus Kindermann},
journal= {arXiv preprint arXiv:1501.00760},
year = {2015}
}