Spin and Valley Filter Based on Two-Dimensional WSe2 Heterostructures

In this work, we investigate the spin and valley transport properties of a $\mathrm{W}{\mathrm{Se}}_{2}$ monolayer placed on top of a ferromagnetic insulator. We are interested in controlling the transport properties by applying external potentials to the system. To obtain spin and valley polarizations, we consider a single- and a double-barrier structure with gate potentials. We analyze how the efficiency of these polarized transport properties depends on the gate-potential intensities and geometrical configurations. Additionally, we investigate how the spin and valley transport properties are modified when an ac potential is applied to the system. We obtain a controllable modulation of the spin and valley polarizations as a function of the intensity and frequency of the ac potential, mainly in the terahertz range. These results validate the proposal of double quantum well structures of $\mathrm{W}{\mathrm{Se}}_{2}$ as candidates to provide spin- and valley-dependent transport within an optimal geometrical parameter regime.