Electronic structure of YbB${}_6$: Is it a Topological Insulator or not?

Abstract

To resolve the controversial issue of the topological nature of the electronic structure of YbB${}_6$, we have made a combined study using density functional theory (DFT) and angle resolved photoemission spectroscopy (ARPES). Accurate determination of the low energy band topology in DFT requires the use of modified Becke-Johnson exchange potential incorporating the spin-orbit coupling and the on-site Coulomb interaction $U$ of Yb $4f$ electrons as large as 7 eV. We have double-checked the DFT result with the more precise GW band calculation. ARPES is done with the non-polar (110) surface termination to avoid band bending and quantum well confinement that have confused ARPES spectra taken on the polar (001) surface termination. Thereby we show definitively that YbB${}_6$ has a topologically trivial B 2$p$-Yb 5$d$ semiconductor band gap, and hence is a non-Kondo non-topological insulator (TI). In agreement with theory, ARPES shows pure divalency for Yb and a $p$-$d$ band gap of 0.3 eV, which clearly rules out both of the previous scenarios of $f$-$d$ band inversion Kondo TI and $p$-$d$ band inversion non-Kondo TI. We have also examined the pressure-dependent electronic structure of YbB${}_6$, and found that the high pressure phase is not a Kondo TI but a \emph{p}-\emph{d} overlap semimetal.

The main text is 6 pages with 4 figures, and the supplementary information contains 6 figures. 11 pages, 10 figures in total To be appeared in Phys. Rev. Lett. (Online publication is around March 16 if no delays.)

References in corpus (12)

• Topological Mott Insulators
• Fractional quantum Hall effect in the absence of Landau levels
• Electronic Structure Calculations with the Tran-Blaha Modified Becke-Johnson Density Functional
• Correlated Topological Insulators with Mixed Valence
• Fractionalized Topological Insulators
• Non-Kondo-like Electronic Structure in the Correlated Rare-Earth Hexaboride YbB${}_6$
• Angle-resolved Photoemission Spectroscopy Study on the Surface States of the Correlated Topological Insulator YbB6
• Pressure-induced quantum phase transitions in topological insulator YbB6
• Topological properties and the dynamical crossover from mixed-valence to Kondo-lattice behavior in golden phase of SmS
• Two distinct topological phases in the mixed valence compound YbB6 and its differences from SmB6
• SmO thin films: a flexible route to correlated flat bands with nontrivial topology
• ARPES insights on the metallic states of YbB6(001): E(k) dispersion, temporal changes and spatial variation

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• Quantum chemical insights into hexaboride electronic structures: correlations within the boron $p$-orbital subsystem
• Exploring itinerant states in divalent hexaborides using rare-earth $L$ edge resonant inelastic X-ray scattering
• Nanoscale Conducting and Insulating Domains on YbB${}_6$
• Electronic correlations and topology in Kondo insulator PuB${}_6$