Non-Kondo-like Electronic Structure in the Correlated Rare-Earth Hexaboride YbB${}_6$

Abstract

We present angle-resolved photoemission studies on the rare-earth hexaboride YbB${}_6$, which has recently been predicted to be a topological Kondo insulator. Our data do not agree with the prediction and instead show that YbB${}_6$ exhibits a novel topological insulator state in the absence of a Kondo mechanism. We find that the Fermi level electronic structure of YbB${}_6$ has three 2D Dirac cone like surface states enclosing the Kramers' points, while the f-orbital which would be relevant for the Kondo mechanism is $\sim 1$ eV below the Fermi level. Our first-principles calculation shows that the topological state which we observe in YbB${}_6$ is due to an inversion between Yb $d$ and B $p$ bands. These experimental and theoretical results provide a new approach for realizing novel correlated topological insulator states in rare-earth materials.

5 pages, 4 figures, Submitted in 2014. Published in 2015, Phys. Rev. Lett. 114, 016403

References in corpus (5)

• 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
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Correlated Topological Insulators with Mixed Valence
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Cited by in corpus (5)

• Two distinct topological phases in the mixed valence compound YbB6 and its differences from SmB6
• Interacting topological phases in thin films of topological mirror Kondo insulators
• Quantum chemical insights into hexaboride electronic structures: correlations within the boron $p$-orbital subsystem
• Nanoscale Conducting and Insulating Domains on YbB${}_6$
• Discovery of magnetic topological crystals