Two-dimensional topological insulators (2DTIs), which host the quantum spin Hall (QSH) effect, are one of the key materials in next-generation spintronic devices. To date, experimental evidence of the QSH effect has only been observed in a few materials, and thus, the search for new 2DTIs is at the forefront of physical and materials science. Here, we report experimental evidence of a 2DTI in the van der Waals material Ta2Pd3Te5. First-principles calculations show that each monolayer of Ta2Pd3Te5 is a 2DTI with weak interlayer interactions. Combined transport, angle-resolved photoemission spectroscopy, and scanning tunneling microscopy measurements confirm the existence of a band gap at the Fermi level and topological edge states inside the gap. These results demonstrate that Ta2Pd3Te5 is a promising material for fabricating spintronic devices based on the QSH effect.
@article{arxiv.2012.07293,
title = {Observation of quantum spin Hall states in Ta$_2$Pd$_3$Te$_5$},
author = {Xuguang Wang and Daiyu Geng and Dayu Yan and Wenqi Hu and Hexu Zhang and Shaosheng Yue and Zhenyu Sun and Shiv Kumar and Kenya Shimada and Peng Cheng and Lan Chen and Simin Nie and Zhijun Wang and Youguo Shi and Yi-Qi Zhang and Kehui Wu and Baojie Feng},
journal= {arXiv preprint arXiv:2012.07293},
year = {2022}
}