Two-dimensional topological insulators with tunable band gaps: Single-layer HgTe and HgSe

Li, Jin; He, Chaoyu; Meng, Lijun; Xiao, Huaping; Tang, Chao; Wei, Xiaolin; Kim, Jinwoong; Kioussis, Nicholas; Stocks, G. M.; Zhong, Jianxin

doi:10.1038/srep14115

Cited by 61 publications

(65 citation statements)

References 61 publications

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“…Although many materials are theoretically predicted to be 2D TIs, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] the experimentally observed QSH effect is limited in HgTe/CdTe and InAs/GaSb quantum wells. Although many materials are theoretically predicted to be 2D TIs, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] the experimentally observed QSH effect is limited in HgTe/CdTe and InAs/GaSb quantum wells.…”

Section: Introductionmentioning

confidence: 99%

Quantum spin hall insulators in strain-modified arsenene

2015

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By means of density functional theory (DFT) computations, we predict that the suitable strain modulation of honeycomb arsenene results in a unique two-dimensional (2D) topological insulator (TI) with a sizable bulk gap (up to 696 meV), which could be characterized and utilized at room temperature. Without considering any spin-orbit coupling, the band inversion occurs around the Gamma (G) point at tensile strains larger than 11.7%, which indicates the quantum spin Hall effect in arsenene at appropriate strains. The nontrivial topological phase was further confirmed by the topological invariant ν = 1 and edge states with a single Dirac-type crossing at the G point. Our results provide a promising strategy for designing 2D TIs with large bulk gaps from commonly used materials.

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Section: Introductionmentioning

confidence: 99%

Quantum spin hall insulators in strain-modified arsenene

2015

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“…Some that a strong spin polarization and ferromagnetism will result due to hole doping. The low-buckled hexagonal HgTe monolayer may also realize a topological nontrivial phase under the appropriate in-plane tensile strain and spin orbital coupling [38]. Small lattice mismatching partners may suitable for heterojunction devices.…”

Section: Lattice Mismatch For Heterojunctionmentioning

confidence: 99%

Monolayer II-VI semiconductors: A first-principles prediction

et al. 2015

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A systematic study of thirty-two honeycomb monolayer II-VI semiconductors is carried out by first-principles methods. While none of the two-dimensional (2D) structures can be energetic stable, it appears that BeO, MgO, CaO, ZnO, CdO, CaS, SrS, SrSe BaTe and HgTe honeycomb monolayer have a good dynamic stability, the stability of the five oxides is consistent with the work published in [H. L. Zhuang et al., Appl. Phys. Lett. 103, 212102 (2013)]. The rest of the compounds in the form of honeycomb are dynamically unstable, revealed by phonon calculations. In addition, according to the molecular dynamic (MD) simulation evolution from these unstable candidates, we also find two extra monolayers dynamically stable, which are tetragonal BaS [P4/nmm (129)] and orthorhombic HgS [P2 1 /m (11)]. The honeycomb monolayers exist in the form of either a planar perfect honeycomb or a low-buckled 2D layer, all of which possess a band gap and most of them are in the ultraviolet region.Interestingly, the dynamically stable SrSe has a gap near visible light, and displays exotic electronic properties with a flat top of the valence band, and hence has a strong spin polarization upon hole doping. The honeycomb HgTe has recently been reported to achieve a topological nontrivial phase under appropriate in-plane tensile strain and spin orbital coupling (SOC) [J. Li et al., arXiv:1412.2528v1 (2014]. Some II-VI partners with less than 5% lattice mismatch may be used to 2 design novel 2D heterojunction devices. If synthesized, potential applications of these 2D II-VI families could include optoelectronics, spintronics and strong correlated electronics.Corresponding

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“…Such interface levels are characterized by Dirac-like energy dispersion originating from the sign reversal of carrier mass at the interface. However, such interface plasmons are essential only when transport via bulk levels of QW is suppressed, which means that Fermi level is in the middle of band gap ofQW, while such band gap is much greater than k B T. This results into the usage of very low temperatures [7] or heavily strained HgTe QW samples with wide band gap (up to 200 meV) [8]. Both approaches are undesirable for construction of real devices, because deep cooling results into bulky and expensive devices, while heavily strained samples could be affected by fast degradation.…”

Section: Plasmons In Rpamentioning

confidence: 99%

Dynamical screening function and plasmons in the wide HgTe quantum wells at high temperatures

Melezhik¹

2018

Semicond. Phys. Quantum Electron. Optoelectron.

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Dynamical screening function of the two-dimensional electron gas in wide HgTe quantum well (QW) has been numerically modelled in this work. Calculations were provided in the Random Phase Approximation (RPA) framework and were based on Lindhard equation. Our simulations directly incorporated non-parabolicity of bulk 2D carriers' spectrum, which was obtained by full 8-band k.p method. In the literature exists data that transport properties of HgTe QWs are explained by graphene-like screening. We provide the comparison of the screening function for the Schrodinger fermions in the inverted bands HgTe QW with the appropriate screening function for graphene monolayer with the Dirac fermions. In addition, the dependencies of HgTe-specific screening function on temperature, scattering wave-vector and frequency are studied with the purpose to study the transport properties under high frequency radiation the QWs structures to be used as THz detectors. Plasmon frequencies of 2DEG in HgTe quantum well under study were calculated in the long-wavelength limit for T = 77 K.

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Two-dimensional topological insulators with tunable band gaps: Single-layer HgTe and HgSe

Cited by 61 publications

References 61 publications

Quantum spin hall insulators in strain-modified arsenene

Quantum spin hall insulators in strain-modified arsenene

Monolayer II-VI semiconductors: A first-principles prediction

Dynamical screening function and plasmons in the wide HgTe quantum wells at high temperatures

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