Observation of Magnetism-Induced Topological Edge State in Antiferromagnetic Topological Insulator MnBi<sub>4</sub>Te<sub>7</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 35695549.
- Also identified by DOI 10.1021/acsnano.2c03622.
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Abstract
Breaking time reversal symmetry in a topological insulator may lead to quantum anomalous Hall effect and axion insulator phase. MnBi<sub>4</sub>Te<sub>7</sub> is a recently discovered antiferromagnetic topological insulator with <i>T</i><sub>N</sub> ∼ 12.5 K, which is composed of an alternatively stacked magnetic layer (MnBi<sub>2</sub>Te<sub>4</sub>) and nonmagnetic layer (Bi<sub>2</sub>Te<sub>3</sub>). By means of scanning tunneling spectroscopy, we clearly observe the electronic state present at a step edge of a magnetic MnBi<sub>2</sub>Te<sub>4</sub> layer but absent at nonmagnetic Bi<sub>2</sub>Te<sub>3</sub> layers at 4.5 K. Furthermore, we find that as the temperature rises above <i>T</i><sub>N</sub> the edge state vanishes, while the point defect induced state persists upon an increase in temperature. These results confirm the observation of magnetism-induced edge states. Our analysis based on an axion insulator theory reveals that the nontrivial topological nature of the observed edge state.