Perfect Spin Filter and Giant Magneto-Resistance in Silicene
Silicene is a two-dimensional topological insulator exhibiting helical edge states. We investigate global and local manipulations at the edges by exposing them to (i) a charge-density-wave order, (ii) a superconductor, (iii) an out-of-plane (anti-)ferromagnetic, and (iv) an in-plane (anti-)ferromagnetic field. We show that these perturbations affect the helical edge states in a different fashion. As a consequence one can realize quantum spin-Hall effect without edge states. In addition, these edge manipulations lead to very promising applications: a perfect spin-filter and a giant magneto-resistance. We also investigate the effect of manipulations on a very few edge-sites of a silicene nanodisk.