Dimensional crossover and topological nature of the thin films of a three-dimensional topological insulator by band gap engineering

Abstract

Identification and control of topological phases in topological thin films offer great opportunity for fundamental research and the fabrication of topology-based devices. Here, combining molecular beam epitaxy, angle-resolved photoemission spectroscopy and ab-initio calculations, we investigate the electronic structure evolution in (Bi1-xInx)2Se3 films with thickness from 2 to 13 quintuple layers. We identify several phases with their characteristic topological nature and evolution between them, i.e., dimensional crossover from a three-dimensional topological insulator with gapless surface state to its two-dimensional counterpart with gapped surface state, and topological phase transition from topological insulator to a normal semiconductor with increasing In concentration x. Furthermore, by introducing In alloying as an external knob of band gap engineering, we experimentally demonstrated the trivial topological nature of Bi2Se3 thin films (below 6 quintuple layers) as two-dimensional gapped systems, in consistent with our theoretical calculations. Our results provide not only a comprehensive phase diagram of (Bi1-xInx)2Se3 and a route to control its phase evolution, but also a practical way to experimentally determine the topological properties of a gapped compound by topological phase transition and band gap engineering.

24 pages, 4 figures

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• Finite-size and composition-driven topological phase transition in (Bi${}_{1-x}$In${}_x$)${}_2$Se${}_3$ thin films

Cited by in corpus (8)

• At the verge of topology: vacancy-driven quantum spin Hall in trivial insulators
• Electrical control of intrinsic nonlinear Hall effect in antiferromagnetic topological insulator sandwiches
• Low-energy modeling of three-dimensional topological insulator nanostructures
• Topological properties of finite-size heterostructures of magnetic topological insulators and superconductors
• Exploring Topological Transport in Pt${}_2$HgSe${}_3$ Nanoribbons: Insights for Spintronic Device Integration
• Photo-induced Multiply Quantized Vortex States in Dirac-like Materials
• Dimensional crossover of class D real-space topological invariants
• Electrical probe of spin-spiral order in quantum spin Hall/spin-spiral magnet van der Waals heterostructures