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Nearly free electrons in a 5d delafossite oxide metal

DOI: 10.1126/sciadv.1500692 DOI Help
PMID: 26601308 PMID Help

Authors: P. Kushwaha (Max Planck Institute for Chemical Physics of Solids) , V. Sunko (Max Planck Institute for Chemical Physics of Solids) , P. J. W. Moll (ETH Zurich) , L. Bawden (University of St Andrews, U.K.) , J. M. Riley (University of St Andrews, U.K.) , N. Nandi (Max Planck Institute for Chemical Physics of Solids) , H. Rosner (Max Planck Institute for Chemical Physics of Solids) , M. P. Schmidt (Max Planck Institute for Chemical Physics of Solids) , F. Arnold (Max Planck Institute for Chemical Physics of Solids) , E. Hassinger (Max Planck Institute for Chemical Physics of Solids) , T. K. Kim (Diamond Light Source) , M. Hoesch (Diamond Light Source) , A. P. Mackenzie (Max Planck Institute for Chemical Physics of Solids) , P. D. C King (University of St Andrews)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Science Advances , VOL 1 (9) , PAGES e1500692

State: Published (Approved)
Published: October 2015
Diamond Proposal Number(s): 10040

Open Access Open Access

Abstract: Understanding the role of electron correlations in strong spin-orbit transition-metal oxides is key to the realization of numerous exotic phases including spin-orbit–assisted Mott insulators, correlated topological solids, and prospective new high-temperature superconductors. To date, most attention has been focused on the 5d iridium-based oxides. We instead consider the Pt-based delafossite oxide PtCoO2. Our transport measurements, performed on single-crystal samples etched to well-defined geometries using focused ion beam techniques, yield a room temperature resistivity of only 2.1 microhm·cm (μΩ-cm), establishing PtCoO2 as the most conductive oxide known. From angle-resolved photoemission and density functional theory, we show that the underlying Fermi surface is a single cylinder of nearly hexagonal cross-section, with very weak dispersion along kz. Despite being predominantly composed of d-orbital character, the conduction band is remarkably steep, with an average effective mass of only 1.14me. Moreover, the sharp spectral features observed in photoemission remain well defined with little additional broadening for more than 500 meV below EF, pointing to suppressed electron-electron scattering. Together, our findings establish PtCoO2 as a model nearly-free–electron system in a 5d delafossite transition-metal oxide.

Subject Areas: Physics, Materials


Instruments: I05-ARPES

Added On: 24/10/2015 20:48

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