Journal
NANO LETTERS
Volume 21, Issue 13, Pages 5828-5833Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.1c01765
Keywords
Plumbene; substrate-orbital-filtering effect; quantum spin Hall insulator; first-principles calculations; tight-bonding model
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Funding
- National Key R&D Program of China [2017YFB0405703]
- National Natural Science Foundation of China [11804210, 51871137, 61434002]
- Natural Science Foundation of Shanxi Province (China) [201901D211406]
- DOE-BES [DE-FG02-04ER46148]
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The study shows that epitaxial growth of plumbene on the BaTe(111) surface can transform the trivial Pb lattice into a quantum spin Hall (QSH) phase with a large gap. Surface adsorption of H or halogen atoms can further increase the gap, demonstrating the potential for exploring large-gap QSH insulators in heavy-metal-based materials.
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 similar to 0.3 eV via a selective substrate-orbital-filtering effect. Tight-binding model analyses show the p(z) orbital in half of the Pb overlayer is selectively removed by the BaTe substrate, leaving behind a p(z)-p(x,y) band inversion. Based on the same working principle, the gap can be further increased to similar to 0.5-0.6 eV by surface adsorption of H or halogen atoms that filters out the other half of the Pb p(z) orbitals. The mechanism of selective 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.
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