Electronic Structure Determination of the Thermoelectric CuRh$_{1-x}$Mg$_{x}$O$_{2}$ using Soft X-Ray Spectroscopies

ORAL

Abstract

Magnesium-doped rhodium oxides with formula unit CuRh$_{1-x}$Mg$_{x}$O$_{2}$ and delafossite-type structure exhibit a high thermoelectric figure of merit at elevated temperatures. The electronic structure of CuRh$_{1-x}$Mg$_{x}$O$_{2}$ has been studied with x-ray emission spectroscopy (XES), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The data reveal that the states at the Fermi level are Rh-derived. Measurements carried out by changing the orientation of the linear photon polarization further indicate that the Rh states have a more localized character along the c-axis, consistent with the layered crystal structure. Given the similarity of the electronic configurations of Co and Rh, these data provide solid experimental evidence that the orbital degrees of freedom of the d$^{6}$ ionic configuration of the states rooted in transport are key for explaining the thermoelectric properties of oxide materials.

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Authors

  • Eric Martin

    Dept. of Physics and Astronomy, The University of Tennessee

  • Paolo Vilmercati

    Dept. of Physics and Astronomy, The University of Tennessee

  • Christine Cheney

    Dept. of Physics and Astronomy, The University of Tennessee

  • Rahul Kulkarni

    Materials and Structures Laboratory, Tokyo Institute of Technology, Jefferson Lab, 12000 Jefferson Avenue, MS 58, Suite 17, Newport News, VA 23606, VirginiaTech, Department of Physics, University of South Alabama, New York University, University of Tennessee Knoxville, Georgia College, North Georgia College \& State Univ., North Carolina Central University, TUNL, James Madison University, Physics Department, Hollins University; JQI, University of Aarhus, University of Tennessee, UNC at Asheville, The College of New Jersey, CERN, Florida Institute of Technology, Mechanical Engineering Department, University of New Mexico, Department of Physics, Florida State University, JINR, Vanderbilt, Tsinghua University, LBNL, Vanderbilt and LBNL, Vanderbilt University, Vanderbilt University, Tsinghua University, Vanderbilt University, LBNL, NBPHS, Vanderbilt University, Dept. of Physics and Astronomy - James Madison University, National High Magnetic Field Laboratory, U. of South Alabama Dept. of Chemistry, U. of South Alabama Dept. of Physics, Ohio State University, Wright State University, Engineering Science and Mechanics, Virginia Tech, US, Department of Nanobio Materials and Electronics, GIST, Republic of Korea, Department of Physics, Virginia Tech

  • Norman Mannella

    Dept. of Physics and Astronomy, The University of Tennessee, University of Tennessee