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arXiv · 2103.02456

Coulomb instabilities of 3D higher-order topological insulators

Peng-Lu Zhao·Xiao-Bin Qiang·Hai-Zhou Lu·X. C. Xie
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Abstract

Topological insulator (TI) is an exciting discovery because of its robustness against disorder and interactions. Recently, higher-order TIs have been attracting increasing attention, because they host 1D topologically-protected hinge states in 3D or 0D corner states in 2D. A significantly critical issue is whether the higher-order TIs also survive interactions, but it is still unexplored. We study the effects of weak Coulomb interaction on a 3D second-order TI, with the help of a renormalization group calculation. We find that the 3D higher-order TIs are always unstable, suffering from two types of topological phase transitions. One is from higher-order TI to TI, the other is to normal insulator (NI). The first type is accompanied by emergent time-reversal and inversion symmetries and has a dynamical critical exponent $κ=1$. The second type does not have the emergent symmetries and has non-universal dynamical critical exponents $κ<1$. Our results may inspire more inspections on the stability of higher-order topological states of matter and related novel quantum criticalities.

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Peng-Lu Zhao, Xiao-Bin Qiang, Hai-Zhou Lu, X. C. Xie. 2021-05-25. Coulomb instabilities of 3D higher-order topological insulators. https://doi.org/10.1103/physrevlett.127.176601

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