Silicene as a topological insulator and its spintronic applications
Wei-Feng Tsai1*
1Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
* presenting author:Wei-Feng Tsai,
Silicene is a two-dimensional crystal of silicon with a hexagonal lattice structure that is related to that of graphene but with atomic bonds that are buckled rather than flat. This buckling confers advantages on silicene over graphene, because it should, in principle, generate both a band gap and polarized spin-states that can be controlled with a perpendicular electric field. Recently we have shown that in the absence of any external field its ground state is topological, exhibiting the quantum spin Hall insulating state with spin currents at edges. Furthermore, a field-gated silicene can possess two gapped Dirac cones exhibiting nearly 100% spin-polarization, situated at the corners of the Brillouin zone. Using these facts, we propose three silicene-based spintronic applications: a spin-filter, a three-terminal Y-shape spin separator, and electrically tunable localized tunneling channels. The first one enables the highly efficient spin-polarization of an output current to be switched electrically, without switching external magnetic fields. The second one causes charge carriers from the incoming terminal to acquire spin polarization imbalance between the two output terminals due to quantum spin Hall effect. The final one can host spin propagating modes via an inhomogeneous electric field setup on a sample. Some recent progress will be mentioned.

Keywords: silicene, topological insulator, spintronics