Three-terminal spin/charge current router

Topological insulator materials have wide applications in electronic and spintronic devices by utilizing the protected edge states. In this paper, based on these topological edge states and energy gaps, we propose some types of spin/charge current router in a three-terminal system consisting of silicene-like nanoribbons (SiNRs). The current is well controlled by the helical edge states of zigzag SiNRs (ZSiNRs) and external fields. Using the tight-binding model and non-equilibrium Green's function theory, we investigate three types of such router. The first type is a spin current shunter which separates the spin-up and spin-down current into different leads. The second type is a spin filter which separates the spin-polarized electrons into one of those leads. The last type is a charge current switcher which switches the charge current from one lead to the other lead. The local current distribution is calculated for the specific electron path. We find that the small Rashba does not destroy the filtering properties of the system. Besides, as an example, we employ the Landauer-Büttiker formula to obtain the current-voltage curves of the first type router and investigate the transmittance reciprocity relations in such a three-terminal system. We believe these proposed spin/charge current routers, which can separate the specific current into the expected lead, have potential applications in the future spintronics designs.