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arXiv · 2508.07351

Experimental Realization of the Topologically Nontrivial Phase in Monolayer Si$_2$Te$_2$

Xiaochun Huang·Lingxiao Zhao·Rui Xiong·Wenbin Li·Bao-tian Wang·Baisheng Sa·Matthias Bode
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Abstract

The free-standing monolayer Si$_2$Te$_2$ (ML-Si$_2$Te$_2$) has been theoretically predicted to host a room-temperature quantum spin Hall phase. However, its experimental realization remains challenge due to the absence of a three-dimensional counterpart. Here, we demonstrate that HfTe$_2$ serves as an ideal substrate for the epitaxial growth of ML-Si$_2$Te$_2$, preserving its topological phase. Scanning tunneling microscopy and spectroscopy confirm a strain-free ${(1 \times 1)}$ lattice of ML-Si$_2$Te$_2$, along with a sizable band gap, which is well captured by first-principles calculations. Moreover, distinct edge states, independent of step geometry and exhibiting a broad spatial distribution, are observed at ML-Si$_2$Te$_2$ step edges, underscoring its topological nature.

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Xiaochun Huang, Lingxiao Zhao, Rui Xiong, Wenbin Li, Bao-tian Wang, Baisheng Sa, Matthias Bode. 2025-08-10. Experimental Realization of the Topologically Nontrivial Phase in Monolayer Si$_2$Te$_2$. https://arxiv.org/abs/2508.07351

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