Grain Size Dependence of Transverse Thermoelectric Transport in the Weyl Semimetal NbP

ORAL

Abstract

Weyl semimetals are excellent candidates for transverse thermoelectric transport via the Nernst effect. The Nernst effect is a thermoelectric phenomenon in which a temperature gradient is applied orthogonal to an applied magnetic field, resulting in a voltage in the mutually perpendicular direction. Single-crystal NbP has shown a large Nernst thermopower, exceeding 800 mV K-1 at 109 K and 9 T [1]. Published work in bulk polycrystalline NbP, with an average grain size of ~100 microns, maintains a large Nernst thermopower, albeit decreased by a factor of ~8 [2]. In this work, we present a grain size study on bulk polycrystalline samples of NbP, where different annealing times result in varying grain sizes. Nernst thermopower continues decrease with decreasing grain size. However, thermal conductivity is also greatly reduced, which is an advantage for thermoelectric transport applications. Via microstructural characterization and thermomagnetic transport measurements, we can determine the optimal grain size for transverse thermoelectric transport applications.
[1] S. J. Watzman et al. Phys. Rev. B 97(16), 161404(R) (2018).
[2] C. Fu et al. Energy Environ. Sci. 11(10), 2813-2830 (2018).

*U.S. Department of Energy Award Number: DE-SC0020154

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Presenters

  • Eleanor F. Scott

    • Department of Mechanical and Materials Engineering, University of Cincinnati
    • University Of Cincinnati

Authors

  • Eleanor F. Scott

    • Department of Mechanical and Materials Engineering, University of Cincinnati
    • University Of Cincinnati

  • Katherine Schlaak

    • Department of Physics, University Of Cincinnati
    • University Of Cincinnati

  • Chenguang Fu

    • Max Planck Institute for Chemical Physics of Solids

  • Safa Khodabakhsh

    • Department of Mechanical and Materials Engineering, University of Cincinnati
    • University Of Cincinnati

  • Satya N. Guin

    • Max Planck Institute for Chemical Physics of Solids

  • Ashley E. Paz y Puente

    • Department of Mechanical and Materials Engineering, University of Cincinnati
    • University Of Cincinnati

  • Claudia Felser

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for the Chemical Physics of Solids
    • Solid State Chemistry, Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute, Dresden, Germany
    • Max Planck, Dresden
    • Max Planck Institute for Chemical Physics of Solids, 01187 Dresden
    • Max Planck Institute for Chemical Physics of Solids,

  • Sarah Watzman

    • Department of Mechanical and Materials Engineering, University of Cincinnati
    • University Of Cincinnati