Unconventional topological phase transition of the Hopf insulator

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Hauptverfasser: Kim, Sunje, Choi, Ysun, Lim, Hyeongmuk, Yang, Bohm-Jung
Format: Preprint
Veröffentlicht: 2024
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author Kim, Sunje
Choi, Ysun
Lim, Hyeongmuk
Yang, Bohm-Jung
author_facet Kim, Sunje
Choi, Ysun
Lim, Hyeongmuk
Yang, Bohm-Jung
contents The topological phase transition between two band insulators is mediated by a gapless state whose low-energy band structure normally contains sufficient information for describing the topology change. In this work, we show that there is a class of topological insulators whose topological phase transition cannot be explained by this conventional paradigm. Taking the Hopf insulator as a representative example, we show that the change of the Hopf invariant requires the information of wave functions as well as the gapless band structure simultaneously. More explicitly, the description of the Hopf invariant change requires us to trace not only the trajectory of Weyl points but also the evolution of the preimages for two distinct eigenstates. We show that such an unconventional topological phase transition originates from the fact that the Hopf invariant is well-defined when all the lower dimensional topological invariants are trivial, which in turn allows us to lift the classifying space of occupied state projectors to the corresponding universal 2-covering space of wave functions. Generalizing our theory to inversion-symmetric 10-fold Altland-Zirnbauer symmetry classes, we provide a complete list of symmetry classes, all of which turn out to have delicate band topology related to the Hopf invariant, where similar unconventional topological phase transitions can appear.
format Preprint
id arxiv_https___arxiv_org_abs_2410_04021
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unconventional topological phase transition of the Hopf insulator
Kim, Sunje
Choi, Ysun
Lim, Hyeongmuk
Yang, Bohm-Jung
Mesoscale and Nanoscale Physics
The topological phase transition between two band insulators is mediated by a gapless state whose low-energy band structure normally contains sufficient information for describing the topology change. In this work, we show that there is a class of topological insulators whose topological phase transition cannot be explained by this conventional paradigm. Taking the Hopf insulator as a representative example, we show that the change of the Hopf invariant requires the information of wave functions as well as the gapless band structure simultaneously. More explicitly, the description of the Hopf invariant change requires us to trace not only the trajectory of Weyl points but also the evolution of the preimages for two distinct eigenstates. We show that such an unconventional topological phase transition originates from the fact that the Hopf invariant is well-defined when all the lower dimensional topological invariants are trivial, which in turn allows us to lift the classifying space of occupied state projectors to the corresponding universal 2-covering space of wave functions. Generalizing our theory to inversion-symmetric 10-fold Altland-Zirnbauer symmetry classes, we provide a complete list of symmetry classes, all of which turn out to have delicate band topology related to the Hopf invariant, where similar unconventional topological phase transitions can appear.
title Unconventional topological phase transition of the Hopf insulator
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2410.04021