Emergent Weyl fermion excitations in TaP explored by 181-Ta quadrupole resonance

Abstract

The ${}^{181}$Ta quadrupole resonance (NQR) technique has been utilized to investigate the microscopic magnetic properties of the Weyl semi-metal TaP. We found 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, ${\nu }_{\mathrm{Q}}$ =19.250 MHz, and an asymmetric parameter of the electric field gradient, $\eta$ = 0.423 were 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/$T_{1}T$) has been measured for the $f_2$-line ($\pm$5/2 $\leftrightarrow$ $\pm$3/2 transition). We found that there exists two regimes with quite different relaxation processes. Above $T\text{*}$ $\approx$ 30 K, a pronounced (1/$T_{1}T$) $\propto$ $T^2$ behavior was found, which is attributed to the magnetic excitations at the Weyl nodes with temperature dependent orbital hyperfine coupling. Below $T\text{*}$, the relaxation is mainly governed by Korringa process with 1/$T_{1}T$ = constant, 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.

Paper + Supplement, 5 figures

References in corpus (8)

• The electronic properties of graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Dirac materials
• Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor
• Nuclear magnetic resonance in the heavy fermion superconductors
• Anomalous hyperfine coupling and nuclear magnetic relaxation in Weyl semimetals
• Hyperfine coupling and spin polarization in the bulk of the topological insulator Bi${}_2$Se${}_3$

Cited by in corpus (23)

• Anomalous Spin Correlations and Mass-Generating Excitonic Instability of Interacting Weyl Fermions
• Optical signature of Weyl electronic structures in tantalum pnictides Ta$Pn$ ($Pn=$ P, As)
• Density Functional Theory based Electric Field Gradient Database
• Exotic Landau Diamagnetism and Weyl-Fermions Excitations in TaAs Revealed by ${}^{75}$As NMR and NQR
• Nuclear spin-lattice relaxation time in TaP and the Knight shift of Weyl semimetals
• Large Diamagnetism and Electromagnetic Duality in Two-dimensional Dirac Electron System
• Giant orbital diamagnetism of three-dimensional Dirac electrons in Sr${}_3$PbO antiperovskite
• S-wave Superconductivity in the Dirac Line-nodal Material CaSb2
• Normal-state properties of the antiperovskite oxide Sr${}_{3-x}$SnO revealed by ${}^{119}$Sn-NMR
• Pressure induced evolution of band structure in black phosphorus studied by ${}^{31}$P-NMR
• Local Observations of Orbital Diamagnetism and Excitation in Three-Dimensional Dirac Fermion Systems Bi${}_{1-x}$Sb${}_x$
• Nuclear spin relaxation rate near the disorder-driven quantum critical point in Weyl fermion systems
• Site-dependent Local Spin Susceptibility and Low-energy Excitation in a Weyl Semimetal WTe${}_2$
• Fast nuclear spin relaxation rates in tilted cone Weyl semimetals: Redshift factors from Korringa relation
• Experimental nuclear quadrupole resonance and computational study of the structurally refined topological semimetal TaSb${}_2$
• Time dependent electric transport in nodal-loop semimetals
• Magnetic correlations in the semimetallic hyper-kagome iridate Na3Ir3O8
• Comparative ${}^{181}$Ta-NQR Study of Weyl Monopnictides TaAs and TaP: Relevance of Weyl Fermion Excitations
• Magnetic-field-induced electronic instability of Weyl-like fermions in compressed black phosphorus
• Magnetically-induced local lattice anomalies and low-frequency nematic fluctuations in the Mott insulator La${}_2$O${}_3$Fe${}_2$Se${}_2$
• ${}^{27}$Al NMR study of the magnetic Weyl semimetal CeAlGe
• 125Te spin-lattice relaxation in a candidate to Weyl semimetals WTe2
• Magneto-Optics of the Weyl Semimetal TaAs in the THz and IR Regions