Experimental realization of the topologically nontrivial phase in monolayer Si₂Te₂.

Authors

Xiaochun Huang, Lingxiao Zhao, Rui Xiong, Wenbin Li, Bao-Tian Wang, Baisheng Sa, Matthias Bode

Published in

Nature communications. Volume 17. Issue 1. Sep 11, 2026. Epub Sep 11, 2026.

Abstract

Quantum spin Hall insulators, with dissipationless edge channels protected by time-reversal symmetry, are promising for low-power and quantum devices. However, experimentally realized examples with sizable nontrivial gaps remain scarce. Monolayer Si₂Te₂ has been theoretically predicted to host a room-temperature quantum spin Hall phase, but the absence of a bulk analog has hindered its experimental realization. Here we show that HfTe₂ provides an ideal van der Waals template for the epitaxial growth of strain-free monolayer Si₂Te₂ while preserving its nontrivial topological phase. Scanning tunneling microscopy and spectroscopy reveal an intact (1×1) lattice and a bulk band gap of  ~ 300 meV, consistent with first-principles calculations. Moreover, pronounced edge states extending ~ 2.0 nm from the island boundary are observed in monolayer Si₂Te₂, exhibiting characteristics expected for topological edge modes. Our results establish monolayer Si₂Te₂ as a large-gap two-dimensional topological-insulator platform for topological phenomena and device concepts at elevated temperatures.

PMID:
42728256
Bibliographic data and abstract were imported from PubMed on 12 Sep 2026.

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