Realization of quantum spin Hall insulator superlattice with emergent multigap-like helical edge states
Abstract
The functional quantum spin Hall insulators (QSHI), protected by time-reversal symmetry against single-particle backscattering, hold great promise for dissipationless quantum electronics. Realization of QSHI with gapped helical edge states, which would enable deterministic on/off switching of the edge-channel conductance, is a key requirement for programmable topological circuits. Here, we report realization of superlattice-modulated QSHI HfTe5 hosting emergent multigap-like helical edge states. Using scanning tunneling microscopy and spectroscopy, we identify a reconstruction-induced periodic superlattice modulation in epitaxial monolayer HfTe5 and directly observe multiple gap-like features in the edge channel, accompanied by a series of sharp peaks in the density of states. Combined with theoretical modelling, we attribute the observed edge gap to the finite-width coupling between the two edges significantly enhanced by the superlattice modulation, whereas the sharp peaks are the manifestations of mini-gaps opening at the reduced Brillouin zone boundaries by the periodic modulation of spin-orbit coupling. Notably, these sharp peaks exhibit clear Zeeman splitting under magnetic fields, consistent with the helical nature of the topological edge states. Our results establish a viable route to engineering gapped helical edge states in QSHI and provide a promising platform for topological devices with desired on/off switchability.
Versions
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BibTeX
@misc{guo2026realization,
title = {{Realization of quantum spin Hall insulator superlattice with emergent multigap-like helical edge states}},
author = {Hui Guo and Xianghe Han and Fang Qin and Xiaoshuai Fu and Hao Peng and Hongqin Xiao and Hengxin Tan and Chen Liu and Zihao Huang and Jiayi Wang and Qian Fang and Rui Chen and Haitao Yang and Wang Yao and Li Huang and Hai-Zhou Lu and Hui Chen and Hong-Jun Gao},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.25732},
eprint = {2609.25732},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25732},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Realization of quantum spin Hall insulator superlattice with emergent multigap-like helical edge states
AU - Hui Guo
AU - Xianghe Han
AU - Fang Qin
AU - Xiaoshuai Fu
AU - Hao Peng
AU - Hongqin Xiao
AU - Hengxin Tan
AU - Chen Liu
AU - Zihao Huang
AU - Jiayi Wang
AU - Qian Fang
AU - Rui Chen
AU - Haitao Yang
AU - Wang Yao
AU - Li Huang
AU - Hai-Zhou Lu
AU - Hui Chen
AU - Hong-Jun Gao
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2609.25732
UR - https://arxiv.org/abs/2609.25732
AB - The functional quantum spin Hall insulators (QSHI), protected by time-reversal symmetry against single-particle backscattering, hold great promise for dissipationless quantum electronics. Realization of QSHI with gapped helical edge states, which would enable deterministic on/off switching of the edge-channel conductance, is a key requirement for programmable topological circuits. Here, we report realization of superlattice-modulated QSHI HfTe5 hosting emergent multigap-like helical edge states. Using scanning tunneling microscopy and spectroscopy, we identify a reconstruction-induced periodic superlattice modulation in epitaxial monolayer HfTe5 and directly observe multiple gap-like features in the edge channel, accompanied by a series of sharp peaks in the density of states. Combined with theoretical modelling, we attribute the observed edge gap to the finite-width coupling between the two edges significantly enhanced by the superlattice modulation, whereas the sharp peaks are the manifestations of mini-gaps opening at the reduced Brillouin zone boundaries by the periodic modulation of spin-orbit coupling. Notably, these sharp peaks exhibit clear Zeeman splitting under magnetic fields, consistent with the helical nature of the topological edge states. Our results establish a viable route to engineering gapped helical edge states in QSHI and provide a promising platform for topological devices with desired on/off switchability.
ER -