Origin of Rashba splitting in the quantized subbands at the Bi sub(2)Se sub(3) surface

We study the band structure of the Bi sub(2)Se sub(3) topological insulator (111) surface using angle-resolved photoemission spectroscopy. We examine the situation where two sets of quantized subbands exhibiting different Rashba spin splitting are created via bending of the conduction (CB) and the v...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2013-08, Vol.88 (8)
Main Authors: Benia, H M, Yaresko, A, Schnyder, A P, Henk, J, Lin, C T, Kern, K, Ast, C R
Format: Article
Language:English
Subjects:
Band structure of solids
Bands
Bending
Condensed matter
Insulators
Mathematical analysis
Orbitals
Splitting
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Summary:We study the band structure of the Bi sub(2)Se sub(3) topological insulator (111) surface using angle-resolved photoemission spectroscopy. We examine the situation where two sets of quantized subbands exhibiting different Rashba spin splitting are created via bending of the conduction (CB) and the valence (VB) bands at the surface. While the CB subbands are strongly Rashba spin split, the VB subbands do not exhibit clear spin splitting. We find that CB and VB experience similar band bending magnitudes, which means, a spin-splitting discrepancy due to different surface potential gradients can be excluded. On the other hand, by comparing the experimental band structure to first-principles LMTO band structure calculations, we find that the strongly spin-orbit coupled Bi 6p orbitals dominate the orbital character of CB, whereas their admixture to VB is rather small. The spin-splitting discrepancy is, therefore, traced back to the difference in spin-orbit coupling between CB and VB in the respective subbands' regions.
ISSN:1098-0121
1550-235X