Topological phase transition and two dimensional topological insulators in Ge-based thin films

Abstract

We discuss possible topological phase transitions in Ge-based thin films of Ge(Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_4$ as a function of layer thickness and Bi concentration $x$ using the first principles density functional theory framework. The bulk material is a topological insulator at $x$ = 1.0 with a single Dirac cone surface state at the surface Brillouin zone center, whereas it is a trivial insulator at $x$ = 0. Through a systematic examination of the band topologies we predict that thin films of Ge(Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_4$ with $x$ = 0.6, 0.8 and 1.0 are candidates for two-dimensional (2D) topological insulators, which would undergo a 2D topological phase transition as a function of $x$. A topological phase diagram for Ge(Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_4$ thin films is presented to help guide their experimental exploration.

7 pages, 5 figures, Accepted for publication in Physical Review B (2012)

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Cited by in corpus (8)

• Colloquium: Topological Band Theory
• Finite-size-effect-induced topological phase transition in a topological crystalline insulator
• Quantum Spin Hall Effect in IV-VI Topological Crystalline Insulators
• Topological phase transition and quantum spin Hall state in TlBiS${}_2$
• Switchable large-gap quantum spin Hall state in two-dimensional MSi${}_2$Z${}_4$ materials class
• Role of surface termination in realizing well-isolated topological surface states within the bulk band gap in TlBiSe${}_2$ and TlBiTe${}_2$
• Observation of a Smoothly Tunable Dirac Point in $Ge(B{i}_{x}S{b}_{1-x}{)}_{2}T{e}_4$
• Magnetically tunable Dirac and Weyl fermions in the Zintl materials family