Stacking-dependent energetics and electronic structure of ultrathin polymorphic V${}_2$VI${}_3$ topological insulator nanofilms

Abstract

Topological insulators represent a paradigm shift in surface physics. The most extensively studied Bi${}_2$Se${}_3$-type topological insulators exhibit layered structures, wherein neighboring layers are weakly bonded by van der Waals interactions. Using first principles density-functional theory calculations, we investigate the impact of the stacking sequence on the energetics and band structure properties of three polymorphs of Bi${}_2$Se${}_3$, Bi${}_2$Te${}_3$, and Sb${}_2$Te${}_3$. Considering their ultrathin films up to 6 nm as a function of its layer thickness, the overall dispersion of the band structure is found to be insensitive to the stacking sequence, while the band gap is highly sensitive, which may also affect the critical thickness for the onset of the topologically nontrivial phase. Our calculations are consistent with both experimental and theoretical results, where available. We further investigate tribological layer slippage, where we find a relatively low energy barrier between two of the considered structures. Both the stacking-dependent band gap and low slippage energy barriers, suggest that polymorphic stacking modification may offer an alternative route for controlling the properties of this new state of matter.

9 pages with 7 figures, accepted in Physical Review B

References in corpus (10)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Topological Insulators with Inversion Symmetry
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Pressure induced Superconductivity in Topological Compound Bi2Te3
• Controlling bulk conductivity in topological insulators: Key role of anti-site defects
• Landau quantization and the thickness limit of topological insulator thin films of Sb2Te3
• First Principles Investigations of the Atomic, Electronic, and Thermoelectric Properties of Equilibrium and Strained Bi2Se3 & Bi2Te3, with van der Waals Interactions
• Evidence for a direct band gap in the topological insulator Bi2Se3 from theory and experiment
• Quasiparticle Effects in the Bulk and Surface-State Bands of Bi2Se3 and Bi2Te3 Topological Insulators
• Commensurate-incommensurate phase transition in bilayer graphene

Cited by in corpus (1)

• Prediction of Tunable Spin-Orbit Gapped Materials for Dark Matter Detection