Electronic structure, spin-orbit coupling, and interlayer interaction in bulk MoS2 and WS2

摘要

We present in-depth measurements of the electronic band structure of thetransition-metal dichalcogenides (TMDs) MoS2 and WS2 using angle-resolvedphotoemission spectroscopy, with focus on the energy splittings in theirvalence bands at the K point of the Brillouin zone. Experimental results areinterpreted in terms of our parallel first-principles computations. We findthat interlayer interaction only weakly contributes to the splitting in bulkWS2, resolving previous debates on its relative strength. We additionally findthat across a range of TMDs, the band gap generally decreases with increasingmagnitude of the valence-band splitting, molecular mass, or ratio of theout-of-plane to in-plane lattice constant. Our results provide an importantreference for future studies of electronic properties of MoS2 and WS2 and theirapplications in spintronics and valleytronics devices.