Spin- and valley-polarized transport and magnetoresistance in asymmetric ferromagnetic WSe2 tunnel junctions

Abstract

Transition metal dichalcogenides (TMDs) offer a new platform for theoretical study of two-dimensional materials and their applications, beyond graphene. Previous studies indicate that monolayers of TMDs become ferromagnetic when put in proximity to conventional ferromagnetic, leading to remarkable spin and valley transport properties when combined with the intrinsic spin-orbit coupling (SOC) inherent in these materials. In this work, we show that a magnetic tunnel junction setup consisting of an asymmetric ferromagnetic/ferromagnetic/normal ${\mathrm{WSe}}_{2}$ junction gives rise to a fully spin- and valley-polarized current for both parallel and antiparallel magnetization configurations in the presence of an off-resonance light. Due to the strong SOC of ${\mathrm{WSe}}_{2}$ together with off-resonance light, both the spin and valley polarizations are tunable and switchable. We also find that the tunneling magnetoresistance (TMR) could be tuned to 1 by off-resonance light. The relatively much stronger SOC in the conduction and valence bands of ${\mathrm{WSe}}_{2}$ compared to other compounds of the dichalcogenides family in collaboration with an off-resonance light leads to significant negative TMR at weak enough exchange fields. In appropriate parameter regimes, the TMR oscillations from negative to positive values can be tuned by the off-resonance light. Our results suggest that magnetic tunnel junctions involving ${\mathrm{WSe}}_{2}$ have very promising potential for applications in magnetic memory and spin and valleytronics devices.