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arXiv · 1509.04419

An anomalous band inversion protected by symmetry in a topological insulator of the Kane-Mele model

Jie-Xiang Yu·J. G. Che
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Abstract

Depositing Au on a graphene derivate, which involves substituting four C atoms with three N atoms in a $3\times 3$ cell graphene, we realized a topological insulator of the Kane-Mele model with a gap of 50~meV surrounding the Dirac point of graphene. In this material, we observed an anomalous band inversion (BI) protected by the symmetry with character $e$ of group C$_{\rm 3V}$. The symmetry constrains two $e$ bands with mirror-symmetry combination (MSC) and mirror-antisymmetry combination (MAC) of Au and N orbitals degenerate at $Γ$, whereas the interaction of $π^*$ of graphene on the $e$-MAC band tends to lift this degenerate, resulting in that the $π^*$ and $e$-MAC band exchange their orbital components near $Γ$, causing thus a discontinued BI.

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Jie-Xiang Yu, J. G. Che. 2016-01-11. An anomalous band inversion protected by symmetry in a topological insulator of the Kane-Mele model. https://doi.org/10.1103/physrevb.93.035449

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