Manipulating Spin-polarized Photocurrent in 2D Transition Metal Dichalcogenides

Manipulating spin polarization of electrons in nonmagnetic semiconductors by means of electric fields or optical fields is an essential theme of the conceptual nonmagnetic semiconductor-based spintronics. Here we experimentally demonstrate a method of generating spin polarization in monolayer transition metal dichalcogenides (TMD) by the circularly polarized optical pumping. The fully spin-polarized photocurrent is achieved through the valley dependent optical selection rules and the spin-valley locking in monolayer WS2, and electrically detected by a lateral spin-valve structure with ferromagnetic contacts. The demonstrated long spin lifetime, the unique valley contrasted physics and the spin-valley locking make monolayer WS2 an unprecedented candidate for semiconductor based spintronics.