Strain-Induced Topological Phase Transitions Covering the [Formula: see text] Indicator in Orthorhombic Li2AuBi

Tan Zhang; Frank Coen; Andrew M Rappe

doi:10.1021/acs.nanolett.3c04279

Strain-Induced Topological Phase Transitions Covering the $Z_{4}$ Indicator in Orthorhombic Li₂AuBi

Nano Lett. 2024 Feb 21;24(7):2210-2217. doi: 10.1021/acs.nanolett.3c04279. Epub 2024 Feb 6.

Authors

Tan Zhang¹, Frank Coen², Andrew M Rappe¹

Affiliations

¹ Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States.
² Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6314, United States.

PMID: 38320301
DOI: 10.1021/acs.nanolett.3c04279

Abstract

The $Z_{4}$ symmetry indicator is widely used to classify topological materials hosting inversion symmetry. We find orthorhombic Li₂AuBi in space group Cmcm is a topological insulator with $Z_{4} = 1$ under no strain via first-principles calculations. Due to small band gaps in the k_z = 0 plane, the band inversions can be selectively induced by moderate external strains to realize phases covering all values of $Z_{4}$ = 1, 2, 3, and 0. Detailed $Z_{4}$ phase diagrams are plotted under various moderate strains. The (001) surface states and their associated Fermi surfaces and spin textures are calculated. The topological surface states have different connectivities and different spin textures for the four different $Z_{4}$ phases. The tunability of topological surface states via moderate strain suggests Li₂AuBi as an attractive topological material for device applications.

Keywords: spin texture; symmetry indicator; topological material; topological phase transition under strain; topological surface state.