Tuning Layer-, Perfect-Spin-, and Valley-Polarized Transport in Transition-Metal-Dichalcogenide Bilayer Junctions

In addition to spin and valley degrees of freedom, a bilayer of transition-metal dichalcogenides (TMDs) exhibits a further degree of freedom, the layer pseudospin, which is associated with the interlayer dynamics. Here, we study, over a wide range of energies, the conditions for the generation and control of the perfect-spin-, valley-, and layer-polarized transport in a nonmagnetic/ferromagnetic/nonmagnetic junction fabricated in AB-stacked bilayer TMDs. We find that, via breaking the inversion and time-reversal symmetries through application of external electric and exchange fields, layer-, perfect-spin-, and valley polarized transport can be achieved and controlled electrically and magnetically. Analyzing effects related to the band structure and the local density of states, the predictions are rationalized, and in particular we expose the role of tuning the band gap and adjusting the charge localization in one specific layer. Within an appropriate parameter regime, an energy interval with contributions from both layers is identified, leading to enhancement of the transmission and conductance. Our results can be useful for pseudospintronic applications in bilayer TMD-based devices.