Photo- and exchange-field controlled line-type resonant peaks and enhanced spin and valley polarizations in a magnetic WSe2 junction

Abstract

Existing resonant tunneling modes in the shape of line-type resonances can improve the transport properties of the junction. Motivated by the unique structural properties of monolayer WSe2 e.g. significant spin–orbitcoupling and large direct band gap, the transport properties of a normal/ferromagnetic/normal WSe2 junction with large incident angles in the presence of exchange field (h), off-resonance light () and gate voltage (U) is studied. In a certain interval of U, the transmission shows a gap with optically controllable width, while outside it, the spin and valley resolved transmissions have an oscillatory behavior with respect to U. By applying (h), an optically (electrically) switchable perfect spin and valley polarizations at all angles of incidence have been found. For large incident angles, the transmission resonances change to spin-valley-dependent separated ideal line-type resonant peaks with respect to U, results in switchable perfect spin and valley polarizations, simultaneously. Furthermore, even in the absence of U, applying h or at large incident angles can give some spin-valley dependent ideal transmission peaks, making h or a transmission valve capable of giving a switchable fully spin-valley filtering effect. These findings suggest some alternate methods for providing high efficiency spin and valley filtering devices based on WSe2.