Polaronic transport and thermoelectricity in Fe<sub>1-<i>x</i></sub>Co<i><sub>x</sub></i>Sb<sub>2</sub>S<sub>4</sub> (<i>x</i> = 0, 0.1, and 0.2)

ORAL

Abstract

Correlated electron materials such as FeSb2 possess the highest thermoelectric power factor in nature and thermoelectric power up to 45 mV K-1. We present a study of Co-doped magnetic semiconductor Fe1-xCoxSb2S4 (x = 0, 0.1, and 0.2), which crystallize in an orthorhombic structure with Pnma space group, similar to FeSb2. In contrast to Fe1-xCoxSb2 and Fe1-xCrxSb2 where electronic transport is dominated by thermal activation and variable range hopping, our results indicate polaronic transport due to the large discrepancy between activation energy for conductivity, Eρ (146 ~ 270 meV), and thermopower, ES (47 ~ 108 meV), in Fe1-xCoxSb2S4. Bulk magnetization and heat capacity measurements of FeSb2S4 show a broad antiferromagnetic transition (TN = 46 K) followed by an additional weak transition (T* = 50 K). The TN and T* slightly decrease with increase in x. This is also reflected in thermal conductivity measurement, indicating strong spin-lattice coupling. Fe1-xCoxSb2S4 shows high value of thermopower (up to ~ 624 μV K-1 at 300 K) and significantly smaller thermal conductivity, a feature desired for potential applications based on FeSb2 materials.

*This work was supported by the U.S. DOE, Office of Science, Basic Energy Sciences as a part of the Computational Materials Science Program.

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Presenters

  • Yu Liu

    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

Authors

  • Yu Liu

    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

  • Chang-Jong Kang

    • Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, USA

  • Eli Stavitski

    • National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA

  • Qianheng Du

    • Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11790, USA

  • Klaus Attenkofer

    • National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA

  • Gabriel Kotliar

    • CMPMS, Brookhaven national lab
    • Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, USA
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory
    • Rutgers University
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Lab
    • Physics and Astronomy Department, Rutgers University
    • Physics and Astronomy, rutgers university

  • Cedomir Petrovic

    • Brookhaven National Laboratory
    • Brookhaven Natl Lab
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
    • Brookhaven National Lab