Design of Antiferromagnetic Second-Order Band Topology with Rotation Topological Invariants in Two Dimensions.
basic_science · Level V
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- Record sourced from PubMed, PMID 38870320.
- Also identified by DOI 10.1021/acs.nanolett.4c01817.
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Abstract
The existence of fractionally quantized topological corner charge serves as a key indicator for two-dimensional (2D) second-order topological insulators (SOTIs), yet it has not been experimentally observed in realistic materials. Here, based on effective model analysis and symmetry arguments, we propose a strategy for achieving SOTI phases with in-gap corner states in 2D systems with antiferromagnetic (AFM) order. We discover that the band topology originates from the interplay between intrinsic spin-orbital coupling and interlayer AFM exchange interactions. Using first-principles calculations, we show that the 2D AFM SOTI phase can be realized in (MnBi<sub>2</sub>Te<sub>4</sub>)(Bi<sub>2</sub>Te<sub>3</sub>)<sub><i>m</i></sub> films. Moreover, we demonstrate that the SOTI states are linked to rotation topological invariants under 3-fold rotation symmetry <i>C</i><sub>3</sub>, resulting in fractionally quantized corner charge, i.e., <math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>n</mi></mrow><mrow><mn>3</mn></mrow></mfrac><mrow><mo>|</mo><mi>e</mi><mo>|</mo></mrow></math> (mod <i>e</i>). Due to the great achievements in (MnBi<sub>2</sub>Te<sub>4</sub>)(Bi<sub>2</sub>Te<sub>3</sub>)<sub><i>m</i></sub> systems, our results providing reliable material candidates for experimentally accessible AFM SOTIs should draw intense attention.