Higher-order topology induced by structural buckling

Journal Article · Thu Sep 09 00:00:00 EDT 2021 · National Science Review

DOI:https://doi.org/10.1093/nsr/nwab170· OSTI ID:1885832

Huang, Huaqing; Liu, Feng

Abstract

Higher-order topological insulator (HOTI) states, such as two-dimension (2D) HOTI featured with topologically protected corner modes at the intersection of two gapped crystalline boundaries, have attracted much recent interest. However, the physical mechanism underlying the formation of HOTI states is not fully understood, which has hindered our fundamental understanding and discovery of HOTI materials. Here we propose a mechanistic approach to induce higher-order topological phases via structural buckling of 2D topological crystalline insulators (TCIs). While in-plane mirror symmetry is broken by structural buckling, which destroys the TCI state, the combination of mirror and rotation symmetry is preserved in the buckled system, which gives rise to the HOTI state. We demonstrate that this approach is generally applicable to various 2D lattices with different symmetries and buckling patterns, opening a horizon of possible materials to realize 2D HOTIs. The HOTIs so generated are also shown to be robust against buckling height fluctuation and in-plane displacement. A concrete example is given for the buckled $$\beta $$-Sb monolayer from first-principles calculations. Our finding not only enriches our fundamental understanding of higher-order topology, but also opens a new route to discovering HOTI materials.

• Sponsoring Organization: USDOE
• Grant/Contract Number: FG02-04ER46148
• OSTI ID: 1885832
• Alternate ID(s): OSTI ID: 1905818
• Journal Information: National Science Review, Journal Name: National Science Review Journal Issue: 8 Vol. 9; ISSN 2095-5138
• Publisher: Oxford University Press
• Country of Publication: China
• Language: English