Tailoring the electronic texture of a topological insulator via its surface orientation

Abstract

Three dimensional topological insulator crystals consist of an insulating bulk enclosed by metallic surfaces, and detailed theoretical predictions about the surface state band topology and spin texture are available. While several topological insulator materials are currently known, the existence and topology of these metallic states have only ever been probed for one particular surface orientation of a given material. For most topological insulators, such as Bi${}_{1-x}$Sb${}_x$ and Bi${}_2$Se${}_3$, this surface is the closed-packed (111) surface and it supports one topologically guaranteed surface state Dirac cone. Here we experimentally realise a non closed-packed surface of a topological insulator, Bi${}_{1-x}$Sb${}_x$(110), and probe the surface state topology by angle-resolved photoemission. As expected, this surface also supports metallic states but the change in surface orientation drastically modifies the band topology, leading to three Dirac cones instead of one, in excellent agreement with the theoretical predictions but in contrast to any other experimentally studied TI surface. This illustrates the possibility to tailor the basic topological properties of the surface via its crystallographic direction. Here it introduces a valley degree of freedom not previously achieved for topological insulator systems.

References in corpus (19)

• Topological Insulators
• Topological Insulators in Three Dimensions
• 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
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological invariants of time-reversal-invariant band structures
• Valley contrasting physics in graphene: magnetic moment and topological transport
• Valley filter and valley valve in graphene
• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Experimental demonstration of the topological surface states protected by the time-reversal symmetry
• Quantum Hall Effect from the Topological Surface States of Strained Bulk HgTe
• Landau Quantization of Massless Dirac Fermions in Topological Insulator
• Correlated Topological Insulators with Mixed Valence
• Topological Surface States and Dirac point tuning in ternary Bi2Te2Se class of topological insulators
• Helical edge and surface states in HgTe quantum wells and bulk insulators
• The role of the spin in quasiparticle interference
• Experimental verification of PbBi${}_2$Te${}_4$ as a 3D topological insulator
• Surface states on a topologically non-trivial semimetal: The case of Sb(110)

Cited by in corpus (8)

• Colloquium: Topological Band Theory
• A conductive topological insulator with colossal spin Hall effect for ultra-low power spin-orbit-torque switching
• Experimental Evidence of the Topological Surface States in Mg3Bi2 Films Grown by Molecular Beam Epitaxy
• Spin-orbit torques and spin Hall magnetoresistance generated by twin-free and amorphous Bi0.9Sb0.1 topological insulator films
• Topological surface states on Bi${}_{1-x}$Sb${}_x$: Dependence on surface orientation, surface termination and stability
• One-dimensional spin texture of Bi(441); Quantum Spin Hall properties without a topological insulator
• Rhombic Fermi surfaces in a ferromagnetic MnGa thin film with perpendicular magnetic anisotropy
• Resonantly enhanced photoemission from topological surface states in MnBi${}_6$Te${}_{10}$