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Emergent quantum confinement at topological insulator surfaces

Bahramy, M.S.
King, P.D.C
Chang, J.
Shi, M.
Patthey, L.
Balakrishnan, G.
Hofmann, Ph.
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Published in Nature Communications. 2012, vol. 3, no. 1159
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 Z2 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 semiconductor-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.
Keywords Physical sciencesCondensed matterMaterials science
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BAHRAMY, M.S. et al. Emergent quantum confinement at topological insulator surfaces. In: Nature Communications, 2012, vol. 3, n° 1159. https://archive-ouverte.unige.ch/unige:42078

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Deposited on : 2014-11-21

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