Intrinsic and extrinsic spin-orbit coupling and spin relaxation in monolayer PtSe2
Abstract
Monolayer PtSe2 is a semiconducting transition metal dichalcogenide characterized by an indirect band gap, space inversion symmetry, and high carrier mobility. Strong intrinsic spin-orbit coupling and the possibility to induce extrinsic spin-orbit fields by gating make PtSe2 attractive for fundamental spin transport studies as well as for potential spintronics applications. We perform a systematic theoretical study of the spin-orbit coupling and spin relaxation in this material. Specifically, we employ first principles methods to obtain the basic orbital and spin-orbital properties of PtSe2, also in the presence of an external transverse electric field. We calculate the spin mixing parameters b2 and the spin-orbit fields for the Bloch states of electrons and holes. This information allows us to predict the spin lifetimes due to the Elliott-Yafet and D'yakonov-Perel mechanisms. We find that b2 is rather large, on the order of 10-2 and 10-1, while varies strongly with doping, being about 103 - 104\,ns-1 for %typical Fermi levels in the interval (10-100) meV, carrier density in the interval 1013-1014\,cm-2 at the electric field of 1 V/nm. We estimate the spin lifetimes to be on the picosecond level.