@article{5cde4678586d4a9abef43e01277125a1,
title = "Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator",
abstract = "Room-temperature realization of macroscopic quantum phases is one of the major pursuits in fundamental physics1,2. The quantum spin Hall phase3–6 is a topological quantum phase that features a two-dimensional insulating bulk and a helical edge state. Here we use vector magnetic field and variable temperature based scanning tunnelling microscopy to provide micro-spectroscopic evidence for a room-temperature quantum spin Hall edge state on the surface of the higher-order topological insulator Bi4Br4. We find that the atomically resolved lattice exhibits a large insulating gap of over 200 meV, and an atomically sharp monolayer step edge hosts an in-gap gapless state, suggesting topological bulk–boundary correspondence. An external magnetic field can gap the edge state, consistent with the time-reversal symmetry protection inherent in the underlying band topology. We further identify the geometrical hybridization of such edge states, which not only supports the Z2 topology of the quantum spin Hall state but also visualizes the building blocks of the higher-order topological insulator phase. Our results further encourage the exploration of high-temperature transport quantization of the putative topological phase reported here.",
author = "Nana Shumiya and Hossain, {Md Shafayat} and Yin, {Jia Xin} and Zhiwei Wang and Maksim Litskevich and Chiho Yoon and Yongkai Li and Ying Yang and Jiang, {Yu Xiao} and Guangming Cheng and Lin, {Yen Chuan} and Qi Zhang and Cheng, {Zi Jia} and Cochran, {Tyler A.} and Daniel Multer and Yang, {Xian P.} and Brian Casas and Chang, {Tay Rong} and Titus Neupert and Zhujun Yuan and Shuang Jia and Hsin Lin and Nan Yao and Luis Balicas and Fan Zhang and Yugui Yao and Hasan, {M. Zahid}",
note = "Funding Information: M.Z.H. acknowledges support from the US Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center and Princeton University. M.Z.H. acknowledges visiting scientist support at Berkeley Lab (Lawrence Berkeley National Laboratory) during the early phases of this work. Theoretical and STM works at Princeton University was supported by the Gordon and Betty Moore Foundation (GBMF9461; M.Z.H.). The theoretical work including ARPES were supported by the US DOE under the Basic Energy Sciences program (grant number DOE/BES DE-FG-02-05ER46200; M.Z.H.). We further acknowledge use of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported by the Princeton Center for Complex Materials, a National Science Foundation Materials Research Science and Engineering Center (DMR-2011750). L.B. is supported by DOE-BES through award DE-SC0002613. C.Y. and F.Z. acknowledge the Texas Advanced Computing Center (TACC) for providing resources that have contributed to the research results reported in this work. The theoretical and computational work at University of Texas at Dallas was supported by the National Science Foundation under grant nos. DMR-1921581 (through the DMREF program), DMR-1945351 (through the CAREER program) and DMR-2105139 (through the CMP program). F.Z. also acknowledges support from the Army Research Office under grant no. W911NF-18-1-0416. T.N. acknowledges support from the European Union{\textquoteright}s Horizon 2020 research and innovation programme (ERC-StG-Neupert-757867-PARATOP). T.-R.C. was supported by the Young Scholar Fellowship Program under a MOST grant for the Columbus Program, MOST111-2636-M-006-014, the Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at the National Cheng Kung University (NCKU), the National Center for Theoretical Sciences (Taiwan). Crystal growth is funded by the National Key Research and Development Program of China (2020YFA0308800), the National Science Foundation of China (NSFC) (Grants No. 92065109, No. 11734003, No. 12061131002), Y.Yao is supported the Strategic Priority Research Program of Chinese Academy of Sciences (XDB30000000). The work in Peking University was supported by CAS Interdisciplinary Innovation Team, the strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB28000000 and the National Natural Science Foundation of China No. 12141002. Theoretical and STS works at Princeton University was supported by the Gordon and Betty Moore Foundation (GBMF4547; M.Z.H.). Funding Information: M.Z.H. acknowledges support from the US Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center and Princeton University. M.Z.H. acknowledges visiting scientist support at Berkeley Lab (Lawrence Berkeley National Laboratory) during the early phases of this work. Theoretical and STM works at Princeton University was supported by the Gordon and Betty Moore Foundation (GBMF9461; M.Z.H.). The theoretical work including ARPES were supported by the US DOE under the Basic Energy Sciences program (grant number DOE/BES DE-FG-02-05ER46200; M.Z.H.). We further acknowledge use of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported by the Princeton Center for Complex Materials, a National Science Foundation Materials Research Science and Engineering Center (DMR-2011750). L.B. is supported by DOE-BES through award DE-SC0002613. C.Y. and F.Z. acknowledge the Texas Advanced Computing Center (TACC) for providing resources that have contributed to the research results reported in this work. The theoretical and computational work at University of Texas at Dallas was supported by the National Science Foundation under grant nos. DMR-1921581 (through the DMREF program), DMR-1945351 (through the CAREER program) and DMR-2105139 (through the CMP program). F.Z. also acknowledges support from the Army Research Office under grant no. W911NF-18-1-0416. T.N. acknowledges support from the European Union{\textquoteright}s Horizon 2020 research and innovation programme (ERC-StG-Neupert-757867-PARATOP). T.-R.C. was supported by the Young Scholar Fellowship Program under a MOST grant for the Columbus Program, MOST111-2636-M-006-014, the Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at the National Cheng Kung University (NCKU), the National Center for Theoretical Sciences (Taiwan). Crystal growth is funded by the National Key Research and Development Program of China (2020YFA0308800), the National Science Foundation of China (NSFC) (Grants No. 92065109, No. 11734003, No. 12061131002), Y.Yao is supported the Strategic Priority Research Program of Chinese Academy of Sciences (XDB30000000). The work in Peking University was supported by CAS Interdisciplinary Innovation Team, the strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB28000000 and the National Natural Science Foundation of China No. 12141002. Theoretical and STS works at Princeton University was supported by the Gordon and Betty Moore Foundation (GBMF4547; M.Z.H.). Publisher Copyright: {\textcopyright} 2022, The Author(s), under exclusive licence to Springer Nature Limited.",
year = "2022",
month = oct,
doi = "10.1038/s41563-022-01304-3",
language = "English (US)",
volume = "21",
pages = "1111--1115",
journal = "Nature Materials",
issn = "1476-1122",
publisher = "Nature Publishing Group",
number = "10",
}