NMR Pulse Dependence of the Nuclear Spin-Spin Relaxation 1/T<sub>2</sub> in Single Crystal and Powdered UTe<sub>2</sub>

ORAL

Abstract

UTe2 is a recently discovered heavy-fermion superconductor exhibiting properties consistent with an odd-parity superconducting state [1]. Initial muon spin relaxation and nuclear magnetic resonance (NMR) measurements on chemical-vapor-transport (CVT) grown samples were interpreted as evidence for FM spin-fluctuation mediated superconductivity [2,3], whereas neutron scattering measurements have detected antiferromagnetic spin fluctuations [4]. Here we use 125Te NMR in powdered and single crystal UTe2 to probe the nature of these fluctuations. The temperature dependence of the spin-spin relaxation rate (1/T2) – which was reportedly evidence for FM spin fluctuations [3] – is observed to be dependent on the details of the NMR pulse sequence. Measurements of the rate 1/T2 at T = 12 K and 35 K show that the apparent relaxation rate decreases with reduced pulse amplitude. This behavior is found to be absent in powdered UTe2 above 10K. Using low amplitude excitation, we investigate the NMR Knight shift through the superconducting Tc.

[1] Matsumura et al, J. Phys. Soc. Jpn. 92, 063701 (2023)

[2] Sundar et al, Phys. Rev. B 100, 140502(R) (2019)

[3] Tokunaga et al, J. Phys. Soc. Jpn. 91, 023707 (2022)

[4] Knafo et al, Phys. Rev. B 104, L100409 (2021)

 

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Presenters

  • Austin James Baker

    • University of California, Los Angeles

Authors

  • Austin James Baker

    • University of California, Los Angeles

  • Maximilian Spitaler

    • ETH Zurich

  • Riku Yamamoto

    • University of California, Los Angeles

  • Michihiro Hirata

    • Los Alamos National Laboratory (LANL)

  • Priscila FS Rosa

    • Los Alamos National Laboratory (LANL)

  • Stuart Brown

    • University of California, Los Angeles