Topological phase driven by confinement effects in Bi bilayers

Lima, Erika Nascimento; Schmidt, T. M.

doi:10.1103/physrevb.91.075432

Cited by 17 publications

(16 citation statements)

References 32 publications

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“…The unique characteristic of TI phase is their gapless boundary state inside a bulk band gap, which is spin-locked due to the protection of time-reversal symmetry (TRS), namely the propagation direction of surface electrons is robustly linked to their spin orientation [6], leading to dissipationless transport edge channels. Although being intensively explored for fundamental research and technological applications, the vast family of 2D materials has been largely underexploited for QSH insulators [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Ethynyl-functionalized stanene film: a promising candidate as large-gap quantum spin Hall insulator

Zhang

et al. 2015

New J. Phys.

152

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Quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices which can be achieved only at extremely low temperature presently. The research for new large-gap QSH insulators is critical for their realistic applications at room temperature. Based on first-principles calculations, we propose a QSH insulator with a sizable bulk gap as large as ∼0.22 eV in stanene film functionalized with the organic molecule ethynyl (SnC 2 H), whose topological electronic properties are highly tunable by the external strain. This large-gap is mainly due to the result of the strong spinorbit coupling related to the p xy orbitals at the Γ point of the honeycomb lattice, significantly different from that consisting of the p z orbital as in free-standing group IV ones. The topological characteristic of SnC 2 H film is confirmed by the Z 2 topological order and an explicit demonstration of the topological helical Dirac type edge states. The SnC 2 H film on BN substrate is observed to support a nontrivial large-gap QSH, which harbors a Dirac cone lying within the band gap. Owing to their high structural stability, this two-dimensional large-gap QSH insulator is promising platforms for topological phenomena and new quantum devices operating at room temperature in spintronics.

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Section: Introductionmentioning

confidence: 99%

Ethynyl-functionalized stanene film: a promising candidate as large-gap quantum spin Hall insulator

Zhang

et al. 2015

New J. Phys.

152

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“…Especially the spin-momentum locked surface states of topological insulating Bi films [13][14][15][16], make them very attractive candidates for spintronic devices. To develop and optimize topological insulators (TIs) towards applications, thin films of high quality are a necessity, as otherwise the exotic electronic properties are hampered by bulk conduction [7,17,18]. To minimize the contribution of the substrate [10], an atomically well defined insulating substrate, providing an infinite potential well barrier, is essential for both future electronic applications as well as to get a deeper understanding on the controllability of Bi growth.…”

Section: Introductionmentioning

confidence: 99%

Controlling the growth of Bi(110) and Bi(111) films on an insulating substrate

et al. 2017

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“…Besides, the counter-propagating edge states exhibit opposite spin-polarization, in accordance with the spin-momentum locking of 1D helical electrons. In addition, the Dirac point located at the band gap are calculated to have a high velocity of ~2.0 × 10 5 m/s, comparable to that of 5.5 × 10 5 m/s in HgTe/CdTe quantum well 7 8 . All these consistently indicate that TlSbX 2 (X = H, F) are ideal 2D TIs.…”

Section: Resultsmentioning

confidence: 80%

“…Their helical edge states are spin-locked due to the protection of time-reversal symmetry (TRS), namely the propagation direction of surface electrons is robustly linked to their spin orientation 6 , leading to dissipationless transport edge channels. However, the working temperature of QSH insulators in experiments like HgTe/CdTe 7 8 and InAs/GaSb films 9 10 are very low (below 10 K), limited by their small energy gap. The search of QSH insulators with large-gap is urgently required.…”

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confidence: 99%

Functionalized Thallium Antimony Films as Excellent Candidates for Large-Gap Quantum Spin Hall Insulator

Zhang

et al. 2016

Sci Rep

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Group III-V films are of great importance for their potential application in spintronics and quantum computing. Search for two-dimensional III-V films with a nontrivial large-gap are quite crucial for the realization of dissipationless transport edge channels using quantum spin Hall (QSH) effects. Here we use first-principles calculations to predict a class of large-gap QSH insulators in functionalized TlSb monolayers (TlSbX2; (X = H, F, Cl, Br, I)), with sizable bulk gaps as large as 0.22 ~ 0.40 eV. The QSH state is identified by Z2 topological invariant together with helical edge states induced by spin-orbit coupling (SOC). Noticeably, the inverted band gap in the nontrivial states can be effectively tuned by the electric field and strain. Additionally, these films on BN substrate also maintain a nontrivial QSH state, which harbors a Dirac cone lying within the band gap. These findings may shed new light in future design and fabrication of QSH insulators based on two-dimensional honeycomb lattices in spintronics.

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Topological phase driven by confinement effects in Bi bilayers

Cited by 17 publications

References 32 publications

Ethynyl-functionalized stanene film: a promising candidate as large-gap quantum spin Hall insulator

Ethynyl-functionalized stanene film: a promising candidate as large-gap quantum spin Hall insulator

Controlling the growth of Bi(110) and Bi(111) films on an insulating substrate

Functionalized Thallium Antimony Films as Excellent Candidates for Large-Gap Quantum Spin Hall Insulator

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