NMR Investigation of the Weyl Semimetal TaAs

ORAL

Abstract

Weyl semimetals are expected to host topologically protected bulk states. Recently 181Ta nuclear quadrupolar resonance (NQR) was used as a bulk probe to investigate the band structure of the Weyl semimetal TaP near the Weyl nodes. [1] This is possible because nuclear spins couple to Weyl fermions via an anomalous hyperfine coupling influencing the temperature-dependent nuclear spin relaxation time T1. [2] Depending on the position of the chemical potential with respect to the Weyl nodes, the temperature-dependent relaxation rate is expected to deviate from the Korringa relation, where 1/T1T = constant. In this work we present 181Ta nuclear magnetic resonance (NMR) study of a single crystal TaAs Weyl semimetal, a material in which the chemical potential is typically closer to the Weyl nodes. The 1/T1T dependence of the ±3/2 <-> ±5/2 transition is measured using progressive saturation, and results are compared to theoretical calculations [2] and results on TaP [1]. The 181Ta quadrupole parameters and Knight shift are also determined from the field and temperature dependence of the resonance frequency.
[1] H. Yasuoka et al., Phys. Rev. Lett. 118, 236403 (2017).
[2] Z. Okvátovity et al., Phys. Rev. B 94, 245141 (2016).

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Presenters

  • Arash Akbari-Sharbaf

    Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC, Institut Quantique and Département de Physique, Université de Sherbrooke, Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada

Authors

  • Arash Akbari-Sharbaf

    Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC, Institut Quantique and Département de Physique, Université de Sherbrooke, Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada

  • Aimé Verrier

    Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC, Institut Quantique and Département de Physique, Université de Sherbrooke, Institut Quantique, Université de Sherbrooke

  • Nityan Nair

    Physics, University of California, Berkeley, Department of Physics, University of California, Berkeley, California

  • James G. Analytis

    Physics, University of California, Berkeley, University of California, Berkeley, Department of Physics, University of California, Berkeley, Department of Physics, University of California, Berkeley, California, University of California Berkeley

  • Jeffrey Quilliam

    Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC, Institut Quantique and Département de Physique, Université de Sherbrooke, Institut Quantique, Université de Sherbrooke, Universite de Sherbrooke, Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada