Surface vs bulk electronic structures of a moderately correlated topological insulator YbB6 revealed by ARPES

N. Xu; C. E. Matt; E. Pomjakushina; J. H. Dil; G. Landolt; J. -Z. Ma; X. Shi; R. S. Dhaka; N. C. Plumb; M. Radovic; V. N. Strocov; T. K. Kim; M. Hoesch; K. Conder; J. Mesot; H. Ding; M. Shi

arXiv · 1405.0165

Surface vs bulk electronic structures of a moderately correlated topological insulator YbB6 revealed by ARPES

N. Xu·C. E. Matt·E. Pomjakushina·J. H. Dil·G. Landolt·J. -Z. Ma·X. Shi·R. S. Dhaka·N. C. Plumb·M. Radovic·V. N. Strocov·T. K. Kim·M. Hoesch·K. Conder·J. Mesot·H. Ding·M. Shi

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Abstract

Systematic angle-resolved photoemission spectroscopy (ARPES) experiments have been carried out to investigate the bulk and (100) surface electronic structures of a topological mixed-valence insulator candidate, YbB6. The bulk states of YbB6 were probed with bulk-sensitive soft X-ray ARPES, which show strong three-dimensionality as required by cubic symmetry. Surprisingly the measured Yb 4f states are located around 1 eV and 2.3 eV below the Fermi level (EF), instead of being near EF as indicated by first principle calculations. The dispersive bands near EF are B 2p states, which hybridize with the 4f states. Using surface-sensitive vacuum-ultraviolet ARPES, we revealed two-dimensional surface states which form three electron-like Fermi surfaces (FSs) with Dirac-cone-like dispersions. The odd number of surface FSs gives the first indication that YbB6 is a moderately correlated topological insulator. The spin-resolved ARPES measurements provide further evidence that these surface states are spin polarized with spin locked to the crystal momentum. We have observed a second set of surface states with different topology (hole-like pockets). Clear folding of the bands suggest their origin from a 1X2 reconstructed surface. The topological property of the reconstructed surface states needs further studies.

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N. Xu, C. E. Matt, E. Pomjakushina, J. H. Dil, G. Landolt, J. -Z. Ma, X. Shi, R. S. Dhaka, N. C. Plumb, M. Radovic, V. N. Strocov, T. K. Kim, M. Hoesch, K. Conder, J. Mesot, H. Ding, M. Shi. 2014-05-01. Surface vs bulk electronic structures of a moderately correlated topological insulator YbB6 revealed by ARPES. https://arxiv.org/abs/1405.0165

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