Emergent quantum confinement at topological insulator surfaces

M. S. Bahramy, Phil King, Alberto De La Torre, J. Chang, M. Shi, L. Patthey, G. Balakrishnan, Ph. Hofmann, R. Arita, N. Nagaosa, Felix Baumberger

Research output: Contribution to journalArticlepeer-review

195 Citations (Scopus)

Abstract

Bismuth-chalchogenides are model examples of three-dimensional topological insulators. Their ideal bulk-truncated surface hosts a single spin-helical surface state, which is the simplest possible surface electronic structure allowed by their non-trivial Z(2) topology. However, real surfaces of such compounds, even if kept in ultra-high vacuum, rapidly develop a much more complex electronic structure whose origin and properties have proved controversial. Here we demonstrate that a conceptually simple model, implementing a semi-conductor-like band bending in a parameter-free tight-binding supercell calculation, can quantitatively explain the entire measured hierarchy of electronic states. In combination with circular dichroism in angle-resolved photoemission experiments, we further uncover a rich three-dimensional spin texture of this surface electronic system, resulting from the non-trivial topology of the bulk band structure. Moreover, our study sheds new light on the surface-bulk connectivity in topological insulators, and reveals how this is modified by quantum confinement.

Original languageEnglish
Article number1159
Number of pages7
JournalNature Communications
Volume3
DOIs
Publication statusPublished - Oct 2012

Keywords

  • LOCALIZED WANNIER FUNCTIONS
  • 2-DIMENSIONAL ELECTRON-GAS
  • SINGLE DIRAC CONE
  • BI2SE3
  • BI2TE3
  • PHASE
  • SPECTROSCOPY
  • STATES
  • BITEI

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