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Quantum anomalous hall effect in two-dimensional dumbbell
stanene via 3d metal-atom adsorption
Huisheng Zhang, Zhongqin Yang*
Department of Physics, Fudan University, Shanghai 200433, 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
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.
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 Crdoped DB stanene. Furthermore, it is also found
that the gap size can be tuned by applied electric
field.