Micro-metric electronic patterning of a topological band structure using a photon beam

Abstract

In an ideal 3D topological insulator (TI), the bulk is insulating and the surface conducting due to the existence of metallic states that are localized on the surface; these are the topological surface states. Quaternary Bi-based compounds of Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$ with finely-tuned bulk stoichiometries are good candidates for realizing ideal 3D TI behavior due to their bulk insulating character. However, despite its insulating bulk in transport experiments, the surface region of Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$ crystals cleaved in ultrahigh vacuum also exhibits occupied states originating from the bulk conduction band. This is due to adsorbate-induced downward band-bending, a phenomenon known from other Bi-based 3D TIs. Here we show, using angle-resolved photoemission, how an EUV light beam of moderate flux can be used to exclude these topologically trivial states from the Fermi level of Bi${}_{1.46}$Sb${}_{0.54}$Te${}_{1.7}$Se${}_{1.3}$ single crystals, thereby re-establishing the purely topological character of the low lying electronic states of the system. We furthermore prove that this process is highly local in nature in this bulk-insulating TI, and are thus able to imprint structures in the spatial energy landscape at the surface. We illustrate this by `writing' micron-sized letters in the Dirac point energy of the system.

7 pages, 3 figures, includes Supplementary Information

References in corpus (12)

• 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
• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator
• Emergent quantum confinement at topological insulator surfaces
• 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
• Dirac states with knobs on: interplay of external parameters and the surface electronic properties of 3D topological insulators
• Josephson supercurrent in a topological insulator without a bulk shunt
• Angle-resolved and core-level photoemission study of interfacing the topological insulator Bi1.5Sb0.5Te1.7Se1.3 with Ag, Nb and Fe
• Realization of an isolated Dirac node and strongly modulated Spin Texture in the topological insulator Bi2Te3

Cited by in corpus (4)

• Persistent Optical Gating of a Topological Insulator
• Trigger of the ubiquitous surface band bending in 3D topological insulators
• Comparative study of rare earth hexaborides using high resolution angle-resolved photoemission
• Quantum oscillations of the topological surface states in low carrier concentration crystals of Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$