Zhang Huisheng, Wang Yingying, Yang Wenjia, Zhang Jingjing, Xu Xiaohong, Liu Feng
Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education and Research Institute of Materials Science, Shanxi Normal University, Linfen 041004, China.
Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
Nano Lett. 2021 Jul 14;21(13):5828-5833. doi: 10.1021/acs.nanolett.1c01765. Epub 2021 Jun 22.
Although Pb harbors a strong spin-orbit coupling effect, pristine plumbene (the last group-IV cousin of graphene) hosts topologically trivial states. Based on first-principles calculations, we demonstrate that epitaxial growth of plumbene on the BaTe(111) surface converts the trivial Pb lattice into a quantum spin Hall (QSH) phase with a large gap of ∼0.3 eV via a substrate-orbital-filtering effect. Tight-binding model analyses show the orbital in half of the Pb overlayer is selectively removed by the BaTe substrate, leaving behind a - band inversion. Based on the same working principle, the gap can be further increased to ∼0.5-0.6 eV by surface adsorption of H or halogen atoms that filters out the other half of the Pb orbitals. The mechanism of substrate-orbital-filtering is general, opening an avenue to explore large-gap QSH insulators in heavy-metal-based materials. It is worth noting that plumbene has already been widely grown on various substrates experimentally.
尽管铅具有很强的自旋轨道耦合效应，但原始的铅烯（石墨烯的最后一个第IV族同类物）呈现出拓扑平凡态。基于第一性原理计算，我们证明，通过衬底轨道过滤效应，在BaTe(111)表面外延生长铅烯可将平凡的铅晶格转变为具有约0.3 eV大带隙的量子自旋霍尔（QSH）相。紧束缚模型分析表明，BaTe衬底选择性地去除了铅覆盖层一半中的轨道，留下一个能带反转。基于相同的工作原理，通过表面吸附H或卤原子过滤掉铅的另一半轨道，带隙可进一步增加到约0.5 - 0.6 eV。衬底轨道过滤机制具有普遍性，为探索重金属基材料中的大带隙QSH绝缘体开辟了一条途径。值得注意的是，实验上铅烯已经在各种衬底上广泛生长。
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