Controllable spin direction in nonmagnetic BX/MX2 (M = Mo or W; X = S, Se and Te) van der Waals heterostructures by switching between the Rashba splitting and valley polarization

A schematic of the spin FET based on the BSe/MoSe 2 heterostructure. The Rashba-type spin splitting can be evoked by a positive electric field and the spin/valley Hall effect is controlled by a negative electric field.