Near-room temperature electrical control of spin and valley Hall effect in monolayer WSe_2 transistors for spintronic applications

摘要

Monolayer transition metal dichalcogenide (TMD) materials have exciting potential for applications in spintronics. Due to the monolayer geometry and strong spin-orbit coupling, they are predicted to have a coupled spin and valley Hall effect (SVHE), where valley-polarized conduction carriers have opposite spin [1, 2, 3]. This could provide a valley-preserved spin Hall effect for switching future magnetic memories. WSe_2 is an attractive 2D material in this context because of its large valence band spin splitting. Lifetimes of spin and valley polarized carriers in monolayer WSe_2 have been measured from 0.7 ns to 1 μs at 10 K [4, 5, 6]. Such long lifetimes combined with reasonable mobilities lead to spin-valley accumulation that can be imaged via the magneto-optical Kerr effect (MOKE). For use in applications, it is necessary to electrically control the SVHE and push it towards room temperature.