2021/03/31 by Peng-Lu Zhao, Xiao-Bin Qiang, Hai-Zhou Lu +1 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.127.176601
7 pages, 4 figures
arxiv created 2021/05/25 · arxiv updated 2021/10/27
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.