Density Functional Study of Ternary Topological Insulator Thin Films

Abstract

Using an ab-initio density functional theory based electronic structure method with a semi-local density approximation, we study thin-film electronic properties of two topological insulators based on ternary compounds of Tl (Thallium) and Bi (Bismuth). We consider TlBiX${}_2$ (X=Se, Te) and Bi${}_2$$X$_2$Y(X,Y=Se,Te)compoundswhichprovidebetterDiraccones,comparedtothemodelbinarycompoundsBi$_2$X$_3$ (X=Se, Te). With this property in combination with a structurally perfect bulk crystal, the latter ternary compound has been found to have improved surface electronic transport in recent experiments. In this article, we discuss the nature of surface states, their locations in the Brillouin zone and their interactions within the bulk region. Our calculations suggest a critical thin film thickness to maintain the Dirac cone which is significantly smaller than that in binary Bi-based compounds. Atomic relaxations or rearrangements are found to affect the Dirac cone in some of these compounds. And with the help of layer-projected surface charge densities, we discuss the penetration depth of the surface states into the bulk region. The electronic spectrum of these ternary compounds agrees very well with the available experimental results.

9 pages, 11 figures, 1 table, Accepted for publication in Physical Review B

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Cited by in corpus (13)

• Topological Insulator Materials
• Colloquium: Topological Band Theory
• Manifestation of Topological Protection in Transport Properties of Epitaxial Bi2Se3 Thin Films
• Topological electronic structure and Weyl semimetal in the TlBiSe${}_2$ class of semiconductors
• Evidence of surface transport and weak anti-localization in single crystal of Bi2Te2Se topological insulator
• Topological insulator Bi2Se3 thin films as an alternative channel material in MOSFETs
• Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator
• Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials
• Dielectric capping effects on binary and ternary topological insulator surface states
• Unconventional topological phase transition from semimetal to insulator in SnBi2Te4: Role of anomalous thermal expansion
• A DFT based first-principles investigation of the physical properties of Bi2Te2Se topological insulator
• Topological delocalization and tuning of surface channel separation in Bi2Se2Te Topological Insulator Thin films
• Gate and Carriers tunable Valley Imbalance in Topological Proximitized Rhombohedral Trilayer Graphene