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| Main Authors: | , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2508.17268 |
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| _version_ | 1866918129782751232 |
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| author | Hu, Wenjie Gong, Jiayi Qiu, Yuhui Yang, Lexian Zhou, Jin-Jian Yao, Yugui |
| author_facet | Hu, Wenjie Gong, Jiayi Qiu, Yuhui Yang, Lexian Zhou, Jin-Jian Yao, Yugui |
| contents | Quasi-one-dimensional bismuth halides offer an exceptional platform for exploring diverse topological phases, yet the nature of the room-temperature topological phase transition in Bi$_4$I$_4$ remains unresolved. While theory predicts the high-temperature $β$-phase to be a strong topological insulator (TI), experiments observe a weak TI. Here we resolve this discrepancy by revealing the critical but previously overlooked role of electron-phonon coupling in driving the topological phase transition. Using our newly developed ab initio framework for phonon-induced band renormalization, we show that thermal phonons alone drive $β$-Bi$_4$I$_4$ from the strong TI predicted by static-lattice calculations to a weak TI above ~180 K. At temperatures where $β$-Bi$_4$I$_4$ is stable, it is a weak TI with calculated surface states closely match experimental results, thereby reconciling theory with experiment. Our work establishes electron-phonon renormalization as essential for determining topological phases and provides a broadly applicable approach for predicting topological materials at finite temperatures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_17268 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Phonons Drive the Topological Phase Transition in Quasi-One-Dimensional Bi$_4$I$_4$ Hu, Wenjie Gong, Jiayi Qiu, Yuhui Yang, Lexian Zhou, Jin-Jian Yao, Yugui Materials Science Strongly Correlated Electrons Quasi-one-dimensional bismuth halides offer an exceptional platform for exploring diverse topological phases, yet the nature of the room-temperature topological phase transition in Bi$_4$I$_4$ remains unresolved. While theory predicts the high-temperature $β$-phase to be a strong topological insulator (TI), experiments observe a weak TI. Here we resolve this discrepancy by revealing the critical but previously overlooked role of electron-phonon coupling in driving the topological phase transition. Using our newly developed ab initio framework for phonon-induced band renormalization, we show that thermal phonons alone drive $β$-Bi$_4$I$_4$ from the strong TI predicted by static-lattice calculations to a weak TI above ~180 K. At temperatures where $β$-Bi$_4$I$_4$ is stable, it is a weak TI with calculated surface states closely match experimental results, thereby reconciling theory with experiment. Our work establishes electron-phonon renormalization as essential for determining topological phases and provides a broadly applicable approach for predicting topological materials at finite temperatures. |
| title | Phonons Drive the Topological Phase Transition in Quasi-One-Dimensional Bi$_4$I$_4$ |
| topic | Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2508.17268 |