Abstract

Layered Transition metal dichalcogenides (TMDs) are fruitful platform for electronics, spintronics, and opto-valleytronics. The monolayer TMDs have a similar crystal structure as staggered graphene and thus various physics predicted for inversion asymmetric graphene also inheres in monolayer TMDs. Especially, valley related physics are of particular importance. The broken inversion symmetry splits six Fermi pockets, locating at the first Brillouin zone edges, into two inequivalent groups (±K). The existence of valley degree of freedom is the base requirement for valleytronics. The broken inversion symmetry also lead to finite and valley-depended Berry curvature, which leads to valley-depended optical selection rule (valley circular dichroism), Zeeman-type spin splitting, and valley Hall effect [1]. After the fundamental investigation of valley circular dichroism in TMDs by polarization-resolved photoluminescence, valley-dependent spin splitting [2] and light-induced valley Hall effect [3] were experimentally observed.

© 2015 Japan Society of Applied Physics, Optical Society of America