Coulomb Instabilities of a Three-Dimensional Higher-Order Topological Insulator

Topological insulators (TIs) are an exciting discovery because of their robustness against disorder and interactions. Recently, second-order TIs have been attracting increasing attention, because they host topologically protected 1D hinge states in 3D or 0D corner states in 2D. A significantly criti...

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Bibliographic Details
Published in:Physical review letters 2021-10, Vol.127 (17), p.1-176601, Article 176601
Main Authors: Zhao, Peng-Lu, Qiang, Xiao-Bin, Lu, Hai-Zhou, Xie, X. C.
Format: Article
Language:English
Subjects:
Phase transitions
Topological insulators
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Summary:Topological insulators (TIs) are an exciting discovery because of their robustness against disorder and interactions. Recently, second-order TIs have been attracting increasing attention, because they host topologically protected 1D hinge states in 3D or 0D corner states in 2D. A significantly critical issue is whether the second-order TIs also survive interactions, but it is still unexplored. We study the effects of weak Coulomb interactions on a 3D second-order TI, with the help of renormalization-group calculations. We find that the 3D second-order TIs are always unstable, suffering from two types of topological phase transitions. One is from second-order TI to TI, the other is to normal insulator. 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 but has nonuniversal 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.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.127.176601