Emergent Weyl Fermion Excitations in TaP Explored by Ta 181 Quadrupole Resonance

Yasuoka H, Kubo T, Kishimoto Y, Kasinathan D, Schmidt M, Yan B, Zhang Y, Tou H, Felser C, Mackenzie AP, Baenitz M (2017)

Publication Type: Journal article

Publication year: 2017

Journal

Physical Review Letters American Physical Society

Book Volume: 118

Article Number: 236403

Journal Issue: 23

DOI: 10.1103/PhysRevLett.118.236403

Abstract

The Ta181 quadrupole resonance [nuclear quadrupole resonance (NQR)] technique is utilized to investigate the microscopic magnetic properties of the Weyl semimetal TaP. We find three zero-field NQR signals associated with the transition between the quadrupole split levels for Ta with I=7/2 nuclear spin. A quadrupole coupling constant, νQ=19.250 MHz, and an asymmetric parameter of the electric field gradient, η=0.423, are extracted, in good agreement with band structure calculations. In order to examine the magnetic excitations, the temperature dependence of the spin-lattice relaxation rate (1/T1T) is measured for the f2 line (±5/2↔±3/2 transition). We find that there exist two regimes with quite different relaxation processes. Above T∗≈30 K, a pronounced (1/T1T) T2 behavior is found, which is attributed to the magnetic excitations at the Weyl nodes with temperature-dependent orbital hyperfine coupling. Below T∗, the relaxation is mainly governed by a Korringa process with 1/T1T=const, accompanied by an additional T-1/2-type dependence to fit our experimental data. We show that Ta NQR is a novel probe for the bulk Weyl fermions and their excitations.

Involved external institutions

Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids DE Germany (DE) Kobe University / 神戸大学 JP Japan (JP)

How to cite

APA:

Yasuoka, H., Kubo, T., Kishimoto, Y., Kasinathan, D., Schmidt, M., Yan, B.,... Baenitz, M. (2017). Emergent Weyl Fermion Excitations in TaP Explored by Ta 181 Quadrupole Resonance. Physical Review Letters, 118(23). https://doi.org/10.1103/PhysRevLett.118.236403

MLA:

Yasuoka, H., et al. "Emergent Weyl Fermion Excitations in TaP Explored by Ta 181 Quadrupole Resonance." Physical Review Letters 118.23 (2017).

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