Year: 2024
Type: article
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.
Source: npj Quantum Materials
Authors: W. X. Zhao, M. Yang, X. Du, Y. D. Li, K. Y. Zhai, Y. Q. Hu, J. F. Han, Y. Huang, Z. K. Liu, Y. G. Yao, J. C. Zhuang, Y. Du, J. J. Zhou, Y. L. Chen, L. X. Yang
Institutions: State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beihang University, Beijing Institute of Technology, ShanghaiTech University, University of Oxford, Collaborative Innovation Center of Quantum Matter, Frontier Science Center for Quantum Information of the Ministry of Education of China
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,790
OpenAlex ID: W4405649607