Origin of anomalous temperature dependence of Nernst effect in narrow-gap semiconductors

ORAL

Abstract

Based on the Boltzmann transport theory, we study the origin of the anomalous temperature dependence of the Nernst coefficient (ν) due to the phonon-drag mechanism. For narrow-gap semiconductors, we find that there are two characteristic temperatures at which a noticeable peak structure appears in ν. Contrarily, the Seebeck coefficient (S) always has only one peak. While the breakdown of the Sondheimer cancellation due to the momentum-dependence of the electron relaxation time is essential for the peak in ν at low T, the contribution of the valence band to the phonon-drag current is essential for the peak at higher T. By considering this mechanism, we successfully reproduce ν and S of FeSb2 for which a gigantic phonon-drag effect is observed experimentally.

[1] R. Masuki, T. Nomoto, R. Arita. arXiv:2010.11001 (2020)

*This work was supported by a Grant-in-Aid for Scientific Research (No. 19K14654, No. 19H05825, and No. 16H06345) from Ministry of Education, Culture, Sports, Science and Technology, and CREST (JPMJCR18T3) from the Japan Science and Technology Agency.

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Presenters

  • Ryota Masuki

    • Univ of Tokyo

Authors

  • Ryota Masuki

    • Univ of Tokyo

  • Takuya Nomoto

    • Univ Tokyo
    • University of Tokyo
    • Univ of Tokyo
    • Department of Applied Physics, Univ of Tokyo
    • Department of Applied Physics, The University of Tokyo
    • Department of Applied Physics, University of Tokyo

  • Ryotaro Arita

    • Univ of Tokyo
    • University of Tokyo
    • Department of Applied Physics, Univ of Tokyo
    • CEMS, RIKEN
    • Department of Applied Physics, The University of Tokyo
    • RIKEN-CEMS