Sensitivity of helical edge states to line substitutional magnetic doping in zigzag silicene nanoribbons

Using the tight-binding model, we investigate the sensitivity of helical edge states to a line magnetic doping in the zigzag silicene nanoribbons (ZSiNRs). We find that it is only sensitive to the doping in the odd-numbered line of the edge region. Moreover, a phase transition from the topological insulator to the spin-resolved semiconductor can be induced by the magnetic doping only in the first line. Accordingly, importantly, the pure spin-up and -down currents come into being in two adjacent energy regions around the Fermi level. Therefore, a spin-current conversion can be realized in the ZSiNRs, which may be useful to the design of controllable spintronic device.