Experimental evidence for the presence of Fermi-arc driven entropy transport in the field-induced Weyl semimetal Bi89Sb11

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.

–

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