Giant spin-orbit-induced spin splitting in two-dimensional transition-metal dichalcogenide semiconductors

Abstract

Fully relativistic first-principles calculations based on density functional theory are performed to study the spin-orbit-induced spin splitting in monolayer systems of the transition-metal dichalcogenides MoS${}_2$, MoSe${}_2$, WS${}_2$, and WSe${}_2$. All these systems are identified as direct-band-gap semiconductors. Giant spin splittings of 148–456 meV result from missing inversion symmetry. Full out-of-plane spin polarization is due to the two-dimensional nature of the electron motion and the potential gradient asymmetry. By suppression of the Dyakonov-Perel spin relaxation, spin lifetimes are expected to be very long. Because of the giant spin splittings, the studied materials have great potential in spintronics applications. DOI: http://dx.doi.org/10.1103/PhysRevB.84.153402 ©2011 American Physical Society