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Evidence for a conducting surface state in FeSi and comparison with SmB<sub>6</sub>

ORAL

Abstract

The recent discovery of a conducting surface state in FeSi suggests the possibility of topological behavior [1]. We further explore this state using magnetoresistance M(H,T) measurements in high magnetic fields H to 60 T, electrical resistivity ρ(T) measurements at high pressures P to 7.6 GPa, and magnetic field modulated microwave spectroscopy (MFMMS). The two energy gaps Δ1 and Δ2 of FeSi from the T-dependence of ρ increased with P up to 7 GPa, followed by a drop coinciding with a sharp suppression on the conducting surface transition temperature. The closing of Δ1 and Δ2 with P was also seen in the suspected topological Kondo insulator SmB6 [2]. The behavior of M(H,T) shows additional evidence for the conducting surface state by comparing the behavior perpendicular and parallel to H. Comparisons of M(H,T) of FeSi and SmB6 show similar behavior. However, the MFMMS results suggests differences in the underlying physics of the surface state in these two compounds.

[1] Y. Fang et al., PNAS 117, 8558 (2019)
[2] S. Gabani et al., PRB 67,172406 (2003)

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Presenters

  • Yuhang Deng

    University of California, San Diego

Authors

  • Yuhang Deng

    University of California, San Diego

  • Alexander Breindel

    University of California, San Diego

  • Camilla Moir

    University of California, San Diego, Physics, University of California San Diego

  • Yuankan Fang

    University of California, San Diego

  • Hongbo Lou

    Center for High Pressure Science &Technology Advanced Research

  • Shubin Li

    Center for High Pressure Science &Technology Advanced Research

  • Qiaoshi Zeng

    Center for High Pressure Science &Technology Advanced Research

  • Lei Shu

    Fudan University

  • Christian T Wolowiec

    University of California, San Diego, Physics Department, University of California, San Diego

  • Ivan Schuller

    University of California, San Diego, Dept. of Physics and Center for Advanced Nanoscience, UCSD, La Jolla, CA, USA, Physics Department, University of California, San Diego, Department of Physics, University of California, San Diego

  • Priscila Rosa

    Los Alamos National Lab, Los Alamos National Laboratory, Quantum Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

  • Zachary Fisk

    University of California, Irvine, Department of Physics and Astronomy, University of California, Department of Physics and Astronomy, University of California Irvine

  • John Singleton

    National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos National Lab, Los Alamos National Laboratory, LANL, NHMFL, National High Magnetic Field Laboratory (NHMFL), Los Alamos

  • M Brian Maple

    Department of Physics, University of California, San Diego, University of California, San Diego, Physics, Univ. of California, San Diego