Stable topological phase transitions without symmetry indications in NaZnSb\(_{1-x}\)Bi\(_x\)

We study topological phase transitions in tetragonal NaZnSb\(_{1-x}\)Bi\(_x\), driven by the chemical composition \(x\). Notably, we examine mirror Chern numbers that change without symmetry indicators. First-principles calculations are performed to show that NaZnSb\(_{1-x}\)Bi\(_x\) experiences con...

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Bibliographic Details
Published in:arXiv.org 2022-04
Main Authors: Jung, Jaemo, Kim, Dongwook, Kim, Youngkuk
Format: Article
Language:English
Subjects:
Chemical composition
Fermions
First principles
Indicators
Phase transitions
Symmetry
Topology
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Summary:We study topological phase transitions in tetragonal NaZnSb\(_{1-x}\)Bi\(_x\), driven by the chemical composition \(x\). Notably, we examine mirror Chern numbers that change without symmetry indicators. First-principles calculations are performed to show that NaZnSb\(_{1-x}\)Bi\(_x\) experiences consecutive topological phase transitions, diagnosed by the strong \(\mathbb Z_{2}\) topological index \(\nu_{0}\) and two mirror Chern numbers \(\mu_{x}\) and \(\mu_{xy}\). As the chemical composition \(x\) increases, the topological invariants (\(\mu_{x}\mu_{xy}\nu_{0}\)) change from \((000)\), \((020)\), \((220)\), to \((111)\) at \(x\) = 0.15, 0.20, and 0.53, respectively. A simplified low-energy effective model is developed to examine the mirror Chern number changes, highlighting the central role of spectator Dirac fermions in avoiding symmetry indicators. Our findings suggest that NaZnSb\(_{1-x}\)Bi\(_{x}\) can be an exciting testbed for the exploration of the interplay between the topology and symmetry.
ISSN:2331-8422