Dirac states with knobs on: interplay of external parameters and the surface electronic properties of 3D topological insulators

Abstract

Topological insulators are a novel materials platform with high applications potential in fields ranging from spintronics to quantum computation. In the ongoing scientific effort to demonstrate controlled manipulation of their electronic structure by external means, stoichiometric variation and surface decoration are two effective approaches that have been followed. In ARPES experiments, both approaches are seen to lead to electronic band structure changes. Such approaches result in variations of the energy position of bulk and surface-related features and the creation of two-dimensional electron gases.The data presented here demonstrate that a third manipulation handle is accessible by utilizing the amount of illumination a topological insulator surface has been exposed to under typical experimental ARPES conditions. Our results show that this new, third, knob acts on an equal footing with stoichiometry and surface decoration as a modifier of the electronic band structure, and that it is in continuous competition with the latter. The data clearly point towards surface photovoltage and photo-induced desorption as the physical phenomena behind modifications of the electronic band structure under exposure to high-flux photons. We show that the interplay of these phenomena can minimize and even eliminate the adsorbate-related surface band bending on typical binary, ternary and quaternary Bi-based topological insulators. Including the influence of the sample temperature, these data set up a framework for the external control of the electronic band structure in topological insulator compounds in an ARPES setting. Four external knobs are available: bulk stoichiometry, surface decoration, temperature and photon exposure. These knobs can be used in conjunction to tune the band energies near the surface and consequently influence the topological properties of the relevant electronic states.

16 pages, 8 figures

References in corpus (15)

• Topological Insulators with Inversion Symmetry
• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit
• Topological origin of subgap conductance in insulating bilayer graphene
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator Bi${}_2$Se${}_3$
• First Principles Studies on 3-Dimentional Strong Topological Insulators: Bi2Te3, Bi2Se3 and Sb2Te3
• Emergent quantum confinement at topological insulator surfaces
• Direct Evidence for the Dirac-Cone Topological Surface States in Ternary Chalcogenide TlBiSe2
• Topological Surface States and Dirac point tuning in ternary Bi2Te2Se class of topological insulators
• Low carrier concentration crystals of the topological insulator Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$: a magnetotransport study
• Photoemission induced gating of topological insulator
• An isolated Dirac cone on the surface of ternary tetradymite-like topological insulators