Electrically tunable band gap in silicene

Drummond, Neil; Zólyomi, Viktor; Falko, Vladimir

doi:10.1103/physrevb.85.075423

Cited by 1,096 publications

(925 citation statements)

References 27 publications

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“…The electronic structure of silicene in a perpendicular electric field has been addressed in Ref. [8] and the results of Drummond and coworkers [9] suggest that variation of the electric field with respect to the strength of the spin-orbit coupling induces a transition between a topological and a band insulator.…”

Section: Introductionmentioning

confidence: 99%

Prediction of a quantum anomalous Hall state in Co-decorated silicene

2014

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Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.

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Section: Introductionmentioning

confidence: 99%

Prediction of a quantum anomalous Hall state in Co-decorated silicene

2014

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“…51 Recent theoretical studies have revealed several remarkable features of silicene such as a large spin-orbit gap at the Dirac point, 52 experimentally accessible quantum spin Hall effect, 53 transition from a topological insulating phase to a band insulator that can be induced by an electric field 54 and electrically tunable band gap. 55 In addition to unique insulator phases such as quantum spin Hall, quantum anomalous Hall and band insulator phases, the emergence of valley-polarized metal phase was also reported very recently. 56 It appears that silicene will be a possible graphene replacement not only due to its graphene-like features but also because of its compatibility to existing silicon-based electronic devices.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of alkali, alkaline-earth, and 3dtransition metal atoms on silicene

2013

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The adsorption characteristics of alkali, alkaline earth and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon, are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, workfunction and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na and K, adsorb to hollow site without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene metalization of silicene takes place. Trends directly related to atomic size, adsorption height, workfunction and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline earth metals on silicene are entirely different from their adsorption on graphene. The adsorption of Be, Mg and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal and semiconducting behavior. For all metal adsorbates the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

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“…This has been termed a valley-spin-polarized metal (VSPM). For (E z /E c ) >1 (for example, the case(c) where the ratio (E z /E c ) is 1.44), the spectrum becomes fully gapped again but the system is a band insulator albeit with unusual chiral properties [18].…”

Section: B the Low-energy Excitation Spectrummentioning

confidence: 99%

Effect of disorder in the transition from topological insulator to valley-spin polarized state in silicene and Germanene

Goswami

2014

Indian J Phys

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We start with the silicene/germanene single-particle Hamiltonian in buckled 2D hexagonal lattices expressed in terms of 4 4 Dirac matrices(γ µ ) in the Weyl basis. The Hamiltonian of these systems comprises of the Dirac kinetic energy, a mass gap term, and the spin-orbit coupling. The second term breaks the sub-lattice symmetry of the silicene's honey-comb structure and generates a gap. The buckled structure generates a staggered sub-lattice potential between silicon atoms at A sites and B sites for an applied electric field E z perpendicular to its plane.Tuning of E z , allows for rich behavior varying from a topological insulator (TI)to a band insulator (BI) with a valley spin-polarized metal (VSPM) at a critical value in between. Thus, the mobile electrons in silicene/germanene are coupled differently, compared to graphene, to an external (tunable)electric field. Our preliminary investigation have shown that, as long as the (non-magnetic) impurity scattering strength V 0 is moderate , i.e. V 0 is of the same order as the intrinsic spin-orbit coupling t so (~ 4 meV), VSPM phase is protected. The effective "two-component Dirac physics" remains valid in this phase. The increase in E z beyond the critical value leads to the valley magnetic moment reversal. The enhancement in V 0 , however, leads to the disappearance of the VSPM phase due to accentuated intra-and inter-valley scattering processes. This disappearance does not occur due to the increase in Rashba spin-orbit coupling effect .

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Electrically tunable band gap in silicene

Cited by 1,096 publications

References 27 publications

Prediction of a quantum anomalous Hall state in Co-decorated silicene

Prediction of a quantum anomalous Hall state in Co-decorated silicene

Adsorption of alkali, alkaline-earth, and 3dtransition metal atoms on silicene

Effect of disorder in the transition from topological insulator to valley-spin polarized state in silicene and Germanene

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