Abundant topological states in silicene with transition metal adatoms

Abstract

Electronic and topological properties of silicene adsorbed with 4$d$ transition metal (TM) atoms are investigated by using $ab$ $initio$ methods together with tight-binding models. All six kinds of TM adatoms (Y to Ru) we studied prefer hollow sites of silicene. The interplay of TM-induced exchange interactions, spin-orbit coupling, and staggered $AB$-sublattice potential triggers abundant topological states, including quantum anomalous Hall (QAH) states, valley Hall states, and valley-polarized metallic states. Particularly, QAH states with different Chern numbers are obtained, which is $\ensuremath{-}2$ in the Nb/Ru doped system and 1 in the Y doped system. Our results indicate that great potential for information processing applications exists in these systems of silicene adsorbed with TM atoms.