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

Abstract

In a topological insulator (TI), if its spin-orbit coupling (SOC) strength is gradually reduced, the TI eventually transforms into a trivial insulator beyond a critical point of SOC, at which point the bulk gap closes: this is the standard description of the topological phase transition (TPT). However, this description of TPT, driven solely by the SOC (or something equivalent) and followed by closing and reopening of the bulk band gap, is valid only for infinite-size samples, and little is known how TPT occurs for finite-size samples. Here, using both systematic transport measurements on interface-engineered(Bi${}_{1-x}$In${}_x$)${}_2$Se${}_3$ thin films and theoretical simulations (with animations in Supporting Information) we show that description of TPT in finite-size samples needs to be substantially modified from the conventional picture of TPT due to surface-state hybridization and bulk confinement effects. We also show that the finite-size TPT is composed of two separate transitions, topological-normal transition (TNT) and metal-insulator transition (MIT) by providing a detailed phase diagram in the two-dimensional phase space of sample size and SOC strength.

16 pages, 3 figures + 14 page appendix To appear in Nano letters

References in corpus (7)

• Topological Insulators with Inversion Symmetry
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Unexpected mass acquisition of Dirac fermions at the quantum phase transition of a topological insulator
• Epitaxial growth of topological insulator Bi2Se3 film on Si(111) with atomically sharp interface
• Topological-Metal to Band-Insulator Transition in (Bi1-xInx)2Se3 Thin Films
• Transport Properties of Topological Insulators: Band Bending, Bulk Metal-to-Insulator Transition, and Weak Anti-Localization
• Robust topological surface states of Bi2Se3 thin films on amorphous SiO2/Si substrate and a large ambipolar gating effect

Cited by in corpus (7)

• Solution to the hole-doping problem and tunable quantum Hall effect in Bi${}_2$Se${}_3$ thin films
• Dimensional crossover and topological nature of the thin films of a three-dimensional topological insulator by band gap engineering
• Magnetic quantum phase transition in Cr-doped Bi2(SexTe1-x)3 driven by the Stark effect
• Quantum-Hall to Insulator Transition in Ultra-low-carrier-density Topological Insulator Films and a Hidden Phase of the Zeroth Landau Level
• Ferromagnetic Anomalous Hall Effect in Cr-doped Bi${}_2$Se${}_3$ Thin Films via Surface-State Engineering
• Observation of optical absorption correlated with surface state of topological insulator
• Non-unique connection between bulk topological invariants and surface physics