Perfect control of spin, valley and spin-valley-coupled currents in bilayer graphene on WSe2 magnetic junction: Effect of spin-valley dependent Fermi level and energy gap

Abstract

We investigate the spin-valley dependent transport properties in a gated bilayer graphene (BG) junction placed on top of WSe2. By means of layer-dependent proximity, the spin–orbit interaction (SOI) is induced in the bottom layer, while the top layer is induced into ferromagnetism by a magnetic insulator. As a result of these differing properties, the Fermi level and energy gap become spin-valley dependent, which could lead to controllable spin- and valley-dependent filtering in the BG system. Our findings predict perfect spin-valley polarization control through gate control, given specific energy and electric field conditions, as well as spin-valley-coupled and spin currents when both the electric-field-induced energy gap and the exchange energy are equal to the SOI strength. We predict that there will be very highly sensitive gate control of −100% to + 100% of spin-valley-coupled polarization for large barrier thickness. Additionally, we predict 100% valley polarization can be controlled by the gate when the exchange energy is equal to the SOI. Furthermore, we found that the performance of the junction to control the polarizations can be enhanced by increasing the thickness of the junction. This work reveals the potential of the BG/WSe2 hybrid structure for spin-valley-current-based electronics, such as spin-, valley-, and spin-valley field-effect transistors.