Authors
Hui Guo, Xianghe Han, Fang Qin, Xiaoshuai Fu, Hao Peng, Hongqin Xiao, Hengxin Tan, Chen Liu, Zihao Huang, Jiayi Wang, Qian Fang, Rui Chen, Haitao Yang, Wang Yao, Li Huang, Hai-Zhou Lu, Hui Chen, Hong-Jun Gao
Published in
Advanced materials (Deerfield Beach, Fla.). Pages e75159. Sep 30, 2026. Epub Sep 30, 2026.
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.
PMID:
42813808
Bibliographic data and abstract were imported from PubMed on 30 Sep 2026.
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