High-temperature quantum spin Hall states in buckled III-V-monolayer/SiO$_{2}

Xia, Yun; Jin, Suhua; Hanke, W.; Claessen, R.; Li, Gang

doi:10.48550/arxiv.2112.13483

Cited by 1 publication

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“…We propose the experimentally feasible monolayer/substrate combination, i.e., Bi-III monolayer on Al 2 O 3 , as a new platform for realizing a large-gap QSH. It represents a promising material candidate similar to recent proposals [63], with high experimental feasibility for epitaxial synthesis. We further tune these QSH systems to large-gap QAH insulators by functionalizing them with nitrogen with the largest bandgap as large as 405 meV.…”

Section: Introductionmentioning

confidence: 71%

“…The potential difference between A and B sublattices reflects the corresponding environmental difference around Bi and In, breaking sublattice symmetry. We note that 𝐻 0 and 𝐻 𝑆𝑂𝐶 are similar to the tight-binding model of Bi-III monolayer on SiO 2 [63]. Additionally, in the current model, a TR symmetry breaking term 𝐻 𝑀 is also introduced, accounting for the Zeeman splitting, which shifts the two spin-degenerate bands up and down with an equal amount of energy.…”

Section: Tight-binding Modelmentioning

confidence: 82%

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Large-gap quantum anomalous Hall states induced by functionalizing buckled Bi-III monolayer/Al$_{2}$O$_{3}$

Jin¹,

Xia²,

Shi³

et al. 2022

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Chiral edge modes inherent to the topological quantum anomalous Hall (QAH) effect are a pivotal topic of contemporary condensed matter research aiming at future quantum technology and application in spintronics. A large topological gap is vital to protecting against thermal fluctuations and thus enabling a higher operating temperature. From first-principle calculations, we propose Al 2 O 3 as an ideal substrate for atomic monolayers consisting of Bi and group-III elements, in which a large-gap quantum spin Hall effect can be realized. Additional half-passivation with nitrogen then suggests a topological phase transition to a large-gap QAH insulator. By effective tight-binding modelling, we demonstrate that Bi-III monolayer/Al 2 O 3 is dominated by 𝑝 𝑥 , 𝑝 𝑦 orbitals, with subdominant 𝑝 𝑧 orbital contributions. The topological phase transition into the QAH is induced by Zeeman splitting, where the off-diagonal spin exchange does not play a significant role. The effective model analysis promises utility far beyond Bi-III monolayer/Al 2 O 3 , as it should generically apply to systems dominated by 𝑝 𝑥 , 𝑝 𝑦 orbitals with a band inversion at Γ.

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Section: Introductionmentioning

confidence: 71%

Section: Tight-binding Modelmentioning

confidence: 82%