Valley-Polarized Metals and Quantum Anomalous Hall Effect in Silicene

Abstract

Silicene is a monolayer of silicon atoms forming a two-dimensional honeycomb lattice, which shares almost every remarkable property with graphene. The low energy structure of silicene is described by Dirac electrons with relatively large spin-orbit interactions due to its buckled structure. The key observation is that the band structure is controllable by applying the electric field to a silicene sheet. We explore the phase diagram of silicene together with exchange field $M$ and by applying electric field $E_z$. There appear quantum anomalous Hall (QAH) insulator, valley polarized metal (VPM), marginal valley polarized metal (M-VPM), quantum spin Hall (QSH) insulator and band insulator (BI). They are characterized by the Chern numbers and/or by the edge modes of a nanoribbon. It is intriguing that electrons have been moved from a conduction band at the K point to a valence band at the K' point for $E_z>0$ in the VPM. We find in the QAH phase that flat gapless edge modes emerge and that spins form a momentum-space skyrmion to yield the Chern number. It is remarkable that a topological quantum phase transition can be induced simply by changing electric field in a single silicene sheet.

4 pages, 4 figures, to be published in Phys. Rev. Lett

References in corpus (7)

• Intrinsic and Rashba Spin-orbit Interactions in Graphene Sheets
• The Helical Liquid and the Edge of Quantum Spin Hall Systems
• Quantum Anomalous Hall Effect in Hg${}_{1-y}$Mn${}_y$Te Quantum Wells
• Quantum Anomalous Hall Effect in Graphene from Rashba and Exchange Effects
• Quantum Spin Hall Effect and Topologically Invariant Chern Numbers
• Robustness of the Spin-Chern number
• Quantum Hall Effects in Silicene

Cited by in corpus (22)

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• Spin-Valleytronics in Silicene: Quantum-Spin-Quantum-Anomalous Hall Insulators and Single-Valley Semimetals
• Adsorption of Alkali, Alkaline Earth and Transition Metal Atoms on Silicene
• Spin-Valley Optical Selection Rule and Strong Circular Dichroism in Silicene
• Optical Signatures of the Tunable Band Gap and Valley-Spin Coupling in Silicene
• The atomic structure of the $\sqrt{3}\times \sqrt{3}$ phase of silicene on Ag(111)
• Spin and valley polarization of plasmons in silicene due to external fields
• Quantum spin Hall effect induced by electric field in silicene
• Spin-polarized current induced by a local exchange field in a silicene nanoribbon
• Topological Phase Transition and Electrically Tunable Diamagnetism in Silicene
• Quasi-Topological Insulator and Trigonal Warping in Gated Bilayer Silicene
• Electrically Engineered Band Gap in Two-Dimensional Ge, Sn, and Pb: A First-Principles and Tight-Binding Approach
• Band structure of silicene on the zirconium diboride (0001) thin film surface - convergence of experiment and calculations in the one-Si-atom Brillouin zone
• Structural stability and energy-gap modulation through atomic protrusion in freestanding bilayer silicene
• Change of an insulator's topological properties by a Hubbard interaction
• Quantum criticality at the Chern-to-normal insulator transition
• Strain-tunable topological quantum phase transition in buckled honeycomb lattices
• Hexagonally Warped Dirac Cones and Topological Phase Transition in Silicene Superstructure
• Single and multiple doping effects on electron transport in zigzag silicene nanoribbons
• Electron-phonon correlations on spin texture of gapped helical Dirac Fermions
• Electrically tunable magnetoplasmons in a monolayer of silicene or germanene
• Variable Coupling Strength of Silicene on Ag(111)