Experimental evidence for the presence of Fermi-arc driven entropy transport in the field-induced Weyl semimetal Bi<sub>89</sub>Sb<sub>11</sub>

ORAL

Abstract

Topologically protected Fermi arc surface states in Weyl semimetals have been predicted to produce a conveyer-belt entropy transport [1]. Related theory talks [2][3] show that Bi89Sb11 alloys become Weyl semimetals in a magnetic field applied along the trigonal direction above a critical value HC. Here, we report a strong field-induced increase in electronic thermal conductivity of Bi89Sb11 single crystals along the trigonal direction in longitudinal magnetic fields H>HC. The Lorenz ratio increases up to 80-fold at H= 9T. We report the temperature, length, and angular dependence of the effect in 5 different samples of Bi-Sb alloys with mobilities up to 2x106 cm2V-1s-1. The effect is absent in fields not oriented along the trigonal direction; when the samples are doped n-type and EF s not at the Weyl point; and in the ordinary semimetal Bi95Sb5. We posit that the large positive magnetothermal conductivity is a unique signature of topologically protected surface states.
[1] McCormick et al., Phys. Rev. B 97 195152 (2018)
[2] Zhang et al., APS March Meeting (2019), submitted for oral presentation.
[3] Sahin et al., APS March Meeting (2019), submitted for oral presentation.

*Funding: NSF DMR-1420451.

–

Presenters

  • Dung Vu

    • Department of Mechanical Engineering, The Ohio State University
    • Department of Mechanical and Aerospace Engineering, The Ohio State University

Authors

  • Dung Vu

    • Department of Mechanical Engineering, The Ohio State University
    • Department of Mechanical and Aerospace Engineering, The Ohio State University

  • Cuneyt Sahin

    • Physics and Astronomy, University of Iowa, Iowa City
    • Department of Physics and Astronomy, University of Iowa
    • Optical Science and Technology Center and Department of Physics and Astronomy, University of Iowa

  • WENJUAN ZHANG

    • Department of Physics, The Ohio State University
    • Department of Physics, Ohio State University

  • Michael Flatté

    • Optical Science and Technology Center and Department of Physics and Astronomy, University of Iowa
    • Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa
    • Physics and Astronomy, University of Iowa, Iowa City
    • University of Iowa
    • Department of Physics and Astronomy, University of Iowa
    • Physics and Astronomy, University of Iowa

  • Nandini Trivedi

    • Ohio State University
    • Department of Physics, The Ohio State University
    • Department of Physics, Ohio State University
    • The Ohio State University
    • Physics, Ohio State University

  • Joseph P C Heremans

    • Department of Mechanical and Aerospace Engineering, The Ohio State University
    • Ohio State University
    • Ohio State Univ - Columbus
    • Department of Mechanical Engineering, The Ohio State University
    • Department of Mechanical and Aerospace Engineering, Department of Physics, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210, USA