Quasi-Topological Insulator and Trigonal Warping in Gated Bilayer Silicene

Abstract

Bilayer silicene has richer physical properties than bilayer graphene due to its buckled structure together with its trigonal symmetric structure. The buckled structure arises from a large ionic radius of silicon, and the trigonal symmetry from a particular way of hopping between two silicenes. It is a topologically trivial insulator since it carries a trivial ${\mathbb{Z}}_2$ topological charge. Nevertheless, its physical properties are more akin to those of a topological insulator than those of a band insulator. Indeed, a bilayer silicene nanoribbon has edge modes which are almost gapless and helical. We may call it a quasi-topological insulator. An important observation is that the band structure is controllable by applying the electric field to a bilayer silicene sheet. We investigate the energy spectrum of bilayer silicene under electric field. Just as monolayer silicene undergoes a phase transition from a topological insulator to a band insulator at a certain electric field, bilayer silicene makes a transition from a quasi-topological insulator to a band insulator beyond a certain critical field. Bilayer silicene is a metal while monolayer silicene is a semimetal at the critical field. Furthermore we find that there are several critical electric fields where the gap closes due to the trigonal warping effect in bilayer silicene.

arXiv comment8 pages, 11 figures, to be published in J. Phys. Soc. Jpn

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Cited by in corpus (14)

• d+id' Chiral Superconductivity in Bilayer Silicene
• Spin-Valley Optical Selection Rule and Strong Circular Dichroism in Silicene
• Resolving the Topological Classification of Bismuth with Topological Defects
• Hexagonally Warped Dirac Cones and Topological Phase Transition in Silicene Superstructure
• Geometrical structure and the electron transport properties of monolayer and bilayer silicene near the semimetal-insulator transition point in tight-binding model
• Topological phase transition from trigonal warping in van der Waals multilayers
• Composition and Stacking Dependent Topology in Bilayers from the Graphene Family
• Interband and intraband transition, dynamical polarization and screening of the monolayer and bilayer silicene in low-energy tight-binding model
• Interplay of Floquet Lifshitz transitions and topological transitions in bilayer Dirac materials
• Anomalous Rabi oscillation and related dynamical polarizations under the off-resonance circularly polarized light
• Moiré-modulated band gap and van Hove singularities in twisted bilayer germanene
• Electronic transport and dynamical polarization in bilayer silicene-like system
• Dynamical polarization and the optical response of silicene and related materials
• Confinement in bilayer graphene via intra- and inter-layer interactions