An interface-modulating spin-valley electron beam splitter and perfect spin-valley filter in a topological-insulator junction

This study proposes a spin-valley electron beam splitter based on the inner-edge states in a topological-insulator junction, which can allocate different ratios of spin-valley current outputs. Since the inner-edge states are associated with the "nearest path selection" mechanism, this device is referred to as the interface-modulating spin-valley electron beam splitter. Additionally, two perfect spin-valley filters in similar topological-insulator junctions are established in this study. Under certain conditions, 100% spin-valley polarized currents can be achieved in one or both output leads. By analyzing the local current distribution, it has been determined that achieving perfect propagation requires spin-valley polarized currents with identical valley, spin, and momentum degrees of freedom. Finally, the impact of disorder effects on filter performance is analyzed to guarantee the robustness of the system. The device proposed in this study holds potential for future advancements in spintronics and valleytronics.