Valley-resolved Fano resonance in monolayer transition metal dichalcogenide nanoribbons with attached stubs

Besides spin, the valley degree of freedom is also a promising candidate as a carrier of information. Spintronics has come a long way, and spin modulation can be realized by quantum interference and the spin-orbit coupling effect. However, how to control the valley degree of freedom using quantum interference is still a problem to be explored. Here, we discover a mechanism for producing valley polarization in a monolayer transition metal dichalcogenide nanoribbon with attached stubs, in which valley-resolved Fano resonance is formed due to the quantum interference of intervalley backscattering. When the quantum interference occurs between the localized states at the edge of the stubs and the continuous channels in the nanoribbon, the transmission dips of the Fano effect are valley polarized. As the number of stubs increases, the valley-polarized transmission dips will split, and valley-resolved minigaps are formed by Fano resonance with intervalley backscattering in the stub superlattice. When the electron incident energy is in these valley-resolved gaps of the superlattice, even with several stubs, the transmission can have a significant valley polarization. Our findings point to an opportunity to realize valley functionalities by quantum interference.