Observation of a pronounced Hebel-Slichter peak in the spin-lattice relaxation rate and implications for gap and pairing symmetry in LaNiGa$_2$

Fuente: arXiv
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Autores principales: Sherpa, P., Hingorani, R., Menon, A., Vinograd, I., Chaffey, C., Dioguardi, A. P., Yamamoto, R., Hirata, M., Ronning, F., Badger, J. R., Klavins, P., Singh, R. R. P., Taufour, V., Curro, N. J.
Formato: Preprint
Publicado: 2025
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author Sherpa, P.
Hingorani, R.
Menon, A.
Vinograd, I.
Chaffey, C.
Dioguardi, A. P.
Yamamoto, R.
Hirata, M.
Ronning, F.
Badger, J. R.
Klavins, P.
Singh, R. R. P.
Taufour, V.
Curro, N. J.
author_facet Sherpa, P.
Hingorani, R.
Menon, A.
Vinograd, I.
Chaffey, C.
Dioguardi, A. P.
Yamamoto, R.
Hirata, M.
Ronning, F.
Badger, J. R.
Klavins, P.
Singh, R. R. P.
Taufour, V.
Curro, N. J.
contents We report a pronounced Hebel-Slichter coherence peak in the zero field nuclear quadrupolar resonance (NQR) spin-lattice relaxation rate of the topological crystalline superconductor LaNiGa$_2$ in the superconducting state. Previously, a two-band internally antisymmetric non-unitary triplet pairing (INT) state was proposed for this system, with equal spin-pairing and two distinct gaps associated with different spins. A detailed examination of the temperature dependence of the NQR data shows that the data best fit an INT model if the two gaps are equal and the model is unitary. Even a tiny non-unitarity with two unequal gaps causes the coherence peak to diminish rapidly and deviate from the data. On the other hand, the data are well-fit by a two-band singlet BCS-like pairing with two distinct gaps consistent with previous measurements. This raises doubts on the identification of non-unitary triplet-pairing with time-reversal symmetry breaking in this material.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23800
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of a pronounced Hebel-Slichter peak in the spin-lattice relaxation rate and implications for gap and pairing symmetry in LaNiGa$_2$
Sherpa, P.
Hingorani, R.
Menon, A.
Vinograd, I.
Chaffey, C.
Dioguardi, A. P.
Yamamoto, R.
Hirata, M.
Ronning, F.
Badger, J. R.
Klavins, P.
Singh, R. R. P.
Taufour, V.
Curro, N. J.
Superconductivity
Strongly Correlated Electrons
We report a pronounced Hebel-Slichter coherence peak in the zero field nuclear quadrupolar resonance (NQR) spin-lattice relaxation rate of the topological crystalline superconductor LaNiGa$_2$ in the superconducting state. Previously, a two-band internally antisymmetric non-unitary triplet pairing (INT) state was proposed for this system, with equal spin-pairing and two distinct gaps associated with different spins. A detailed examination of the temperature dependence of the NQR data shows that the data best fit an INT model if the two gaps are equal and the model is unitary. Even a tiny non-unitarity with two unequal gaps causes the coherence peak to diminish rapidly and deviate from the data. On the other hand, the data are well-fit by a two-band singlet BCS-like pairing with two distinct gaps consistent with previous measurements. This raises doubts on the identification of non-unitary triplet-pairing with time-reversal symmetry breaking in this material.
title Observation of a pronounced Hebel-Slichter peak in the spin-lattice relaxation rate and implications for gap and pairing symmetry in LaNiGa$_2$
topic Superconductivity
Strongly Correlated Electrons
url https://arxiv.org/abs/2510.23800