Topological phase transition in quasi-one-dimensional bismuth iodide Bi4I4
Abstract Quasi-one-dimensional (quasi-1D) bismuth iodide Bi4I4 exhibits versatile topological phases of matter including weak topological insulator (WTI) and higher-order topological insulator (HOTI) phases with high tunability in response to external parameters. In this work, performing laser-based...
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2024-12-01
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| Series: | npj Quantum Materials |
| Online Access: | https://doi.org/10.1038/s41535-024-00711-w |
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| Summary: | Abstract Quasi-one-dimensional (quasi-1D) bismuth iodide Bi4I4 exhibits versatile topological phases of matter including weak topological insulator (WTI) and higher-order topological insulator (HOTI) phases with high tunability in response to external parameters. In this work, performing laser-based angle-resolved photoemission spectroscopy with submicron spatial resolution (micro-ARPES), we reveal the presence of an energy gap on the (100) surface of the low-temperature α-Bi4I4, providing spectroscopic evidence for the HOTI phase. Conversely, the high-temperature β-Bi4I4 harbors gapless Dirac fermions on the (100) surface alongside gapped states on the (001) surface, thereby establishing a WTI phase. By tracking the temperature evolution of the (100) surface states, we unveil a thermal hysteresis of the surface gap in line with the α-β structural phase transition. Our findings directly evidence a temperature-induced topological phase transition from WTI to HOTI in Bi4I4, which paves the way to its potential applications at room temperature. |
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| ISSN: | 2397-4648 |