Electron delocalization in gate-tunable gapless silicene

Zhang, Yanyang; Tsai, Wei-Feng; Chang, Kai; An, Xuhong; Zhang, G. P.; Xie, Xiaoming; Li, Shu-Shen

doi:10.1103/physrevb.88.125431

Cited by 15 publications

(10 citation statements)

References 37 publications

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“…[40] However, in the calculations, the intervalley scattering can be neglected because of a slight impact on the transport properties in our considered system. [41,42] We find that the tunneling transmission is asymmetric with respect to the in-plane momentum k y for P configuration but symmetric about k y for AP configuration. The interplay of massive electrons with spin-orbit coupling in silicene results in a spin-valley dependent gap.…”

Section: Introductionmentioning

confidence: 74%

Spin-valley-dependent transport and giant tunneling magnetoresistance in silicene with periodic electromagnetic modulations

Liu¹,

Shao²,

Zhou³

et al. 2017

Chinese Phys. B

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The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved in an incident energy range which can be controlled by the electric gate voltage. For the parallel magnetization configuration, the transmission is asymmetric with respect to the incident angle θ , and electrons with a very large negative incident angle can always transmit in propagating modes for one of the spin-valley filtered states under a certain electromagnetic condition. But for the antiparallel configuration, the transmission is symmetric about θ and there is no such transmission channel. The difference of the transmission between the two configurations leads to a giant tunneling magnetoresistance (TMR) effect. The TMR can reach to 100% in a certain Fermi energy interval around the electrostatic potential. This energy interval can be adjusted significantly by the magnetic field and/or electric gate voltage. The results obtained may be useful for future valleytronic and spintronic applications, as well as magnetoresistance device based on silicene.

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Section: Introductionmentioning

confidence: 74%

Spin-valley-dependent transport and giant tunneling magnetoresistance in silicene with periodic electromagnetic modulations

Liu¹,

Shao²,

Zhou³

et al. 2017

Chinese Phys. B

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“…After that, σ int xy grows remarkably to a considerable but non-quantized value ∼ 0.35 e 2 h at W ∼ 10, before the localization (σ int xy ∼ 0) at strong disorder W = 15. Such an emergence of nonzero σ int xy under increasing disorder is not rare in systems without particle-hole symmetry, and can be attributed to disorder induced band inversion [30,31,36,56]. The nonquantization of σ int xy suggests that the system is in the metallic state, similar to that before the appearance of topological Anderson insulator [31,35,36].…”

Section: Topologically Trivial Phasementioning

confidence: 94%

“…Such an emergence of nonzero σ int xy under increasing disorder is not rare in systems without particle-hole symmetry, and can be attributed to disorder induced band inversion [30,31,36,56]. The nonquantization of σ int xy suggests that the system is in the metallic state, similar to that before the appearance of topological Anderson insulator [31,35,36]. However, since a stable energy gap or mobility gap cannot be formed before another disorder induced band inversion into a trivial Anderson insulator at strong disorder [29][30][31], this system cannot develop into a topological Anderson insulator with a quantized topological invariant (Chern number here).…”

Section: Topologically Trivial Phasementioning

confidence: 99%

“…Most researches of OM so far have been focused on clean crystals. It is well known that strong disorder will eventually induce localization [28][29][30][31][32]. Disorder also leads to rich phenomena in topological materials even in two dimensions, for example, the topological Anderson insulator [30,33,34] and the topological metal [35,36].…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of disorder on the orbital magnetization in two dimensions

Wang

Zhang

Guan

et al. 2020

J. Phys.: Condens. Matter

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The modern theory of orbital magnetization (OM) was developed by using Wannier function method, which has a formalism similar with the Berry phase. In this manuscript, we perform a numerical study on the fate of the OM under disorder, by using this method on the Haldane model in two dimensions, which can be tuned between a normal insulator or a Chern insulator at half filling. The effects of increasing disorder on OM for both cases are simulated. Energy renormalization shifts are observed in the weak disorder regime and topologically trivial case, which was predicted by a self-consistent T-matrix approximation. Besides this, two other phenomena can be seen. One is the localization trend of the band orbital magnetization. The other is the remarkable contribution from topological chiral states arising from nonzero Chern number or large value of integrated Berry curvature. If the fermi energy is fixed at the gap center of the clean system, there is an enhancement of |M | at the intermediate disorder, for both cases of normal and Chern insulators, which can be attributed to the disorder induced topological metal state before localization.

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“…It is clear that the numerical calculations should be supported by a simple but adequate model presenting the exact analytic solutions. The theory of the modification of the spectrum of graphene caused by an increase in the concentration of point impurities was developed in works [5][6][7], where the possibility of the metal-dielectric transition was predicted, and the dominant role of a quasigap filled by localized states in the scattering by pairs and triples of impurity centers was indicated.…”

Section: Introductionmentioning

confidence: 99%

Behavior of the Energy Spectrum and Electric Conduction of Doped Graphene

et al. 2020

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We consider the effect of atomic impurities on the energy spectrum and electrical conductance of graphene. As is known, the ordering of atomic impurities at the nodes of a crystal lattice modifies the graphene spectrum of energy, yielding a gap in it. Assuming a Fermi level within the gap domain, the electrical conductance diverges at the ordering of graphene. Hence, we can conclude about the presence of a metal–dielectric transition. On the other hand, for a Fermi level occurring outside of the gap, we see an increase in the electrical conductance as a function of the order parameter. The analytic formulas obtained in the Lifshitz one-electron strong-coupling model, describing the one-electron states of graphene doped with substitutional impurity atoms in the limiting case of weak scattering, are compared to the results of numerical calculations. To determine the dependence of the energy spectrum and electrical conductance on the order parameter, we consider both the limiting case of weak scattering and the case of finite scattering potential. The contributions of the scattering of electrons on a vapor of atoms to the density of states and the electrical conductance of graphene with an admixture of interstitial atoms are studied within numerical methods. It is shown that an increase in the electrical conductance with the order parameter is a result of both the growth of the density of states at the Fermi level and the time of relaxation of electron states. We have demonstrated the presence of a domain of localized extrinsic states on the edges of the energy gap arising at the ordering of atoms of the admixture. If the Fermi level falls in the indicated spectral regions, the electrical conductance of graphene is significantly affected by the scattering of electrons on clusters of two or more atoms, and the approximation of coherent potential fails in this case.

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Electron delocalization in gate-tunable gapless silicene

Cited by 15 publications

References 37 publications

Spin-valley-dependent transport and giant tunneling magnetoresistance in silicene with periodic electromagnetic modulations

Spin-valley-dependent transport and giant tunneling magnetoresistance in silicene with periodic electromagnetic modulations

Numerical study of disorder on the orbital magnetization in two dimensions

Behavior of the Energy Spectrum and Electric Conduction of Doped Graphene

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