1. Quantum anomalous hall effect in two-dimensional dumbbell stanene via 3d metal-atom adsorption
Huisheng Zhang, Zhongqin Yang*
Department of Physics, Fudan University, Shanghai , China
Inroduction
Topological insulators (TIs), have aroused considerable attention in recent years as they are very interesting for fundamental condensed matter physics and material science. Based on TIs, many intriguing phenomena such as giant magnetoelectric effects, and Majorana fermions, quantum spin Hall (QSH) effect, and quantum anomalous Hall (QAH) effect are predicted, which would result in device paradigms for spintronics and quantum computation. The first experimental observation of QAH effect was in Cr doped (Bi,Sb)2Te3 film, which is a milestone discovery searching for novel topological states. Here, we investigate the topological property of 2D dumbbell stanene (DB) adsorbed with Cr atom.
FIG. 2. The band structures of Cr-doped DB stanene (a) without and (b) with SOC. The black and red curves express the spin-up and spin-down bands, respectively.
Results
FIG. 3. (a) Band structures for Cr-doped DB stanene with SOC by using DFT methods (solid black curves) and Wannier interpretation (open red circles). The blue dots denoted the Berry curvatures [in atomic units (a.u.)] for the whole valence bands. (b) The electric field effect on the gap size.
Conclusion
We mainly investigate topological property of two-dimensional DB stanene adsorbed with Cr atom. The results show that the band inversion induced by spin-orbit couping (SOC) occurs at the Γ point and the gap size is about 8.5 meV. The nonvanishing C = -1 indicates the insulating state is topologically nontrivial, signifying the realization of the interesting QAH effect in Cr-doped DB stanene. Furthermore, it is also found that the gap size can be tuned by applied electric field.
FIG. 1. Top (a) and side (b) view of DB stanene. Three adsorption sites (H1, H2 and T) are indicated in (a) and (b). The solid black and dashed red lines denote 2 × 2 supercell and 1 × 1 primitive cell, respectively. Green sphere denotes Cr atom and atrovirens (blue) sphere denotes in(out) plane Sn atoms. h and l represent the height of the DB and the distance between the neighboring DB, respectively.