Superconducting Order Parameter in UTe<sub>2</sub> Determined by Knight Shift Measurement

Fujibayashi, Hiroki; Nakamine, Genki; Kinjo, Katsuki; Kitagawa, Shunsaku; Ishida, K.; Tokunaga, Y.; Sakai, Hironori; Kambe, S.; Nakamura, Ai; Shimizu, Yusei; Homma, Yoshiya; Li, Dexin; Honda, Fuminori; Aoki, Dai

doi:10.7566/jpsj.91.043705

Cited by 49 publications

(35 citation statements)

References 24 publications

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“…3(c). It is noteworthy that ∆K was near zero in the SC state for values above 15 T. A similar ∆K ∼ 0 trend was previously observed in a-axis Knight-shift measurement results for the LHSC state, where the dominant SC spin component occurred along the a axis [25]. Thus, these results indicate that b-axis spin-polarized superconductivity is induced by a b-axis magnetic field.…”

supporting

confidence: 87%

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Kinjo¹,

Fujibayashi²,

Kitagawa³

et al. 2022

Preprint

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UTe2 is a recently discovered spin-triplet superconductor. One of the characteristic features of UTe2 is a magnetic field (H)-boosted superconductivity above 16 T when H is applied exactly parallel to the b axis. To date, this superconducting (SC) state has not been thoroughly investigated, and the SC properties as well as the spin state of this high-H SC (HHSC) phase are not well understood. In this study, we performed AC magnetic susceptibility and nuclear magnetic resonance (NMR) measurements and found that, up to 24.8 T, the HHSC state is intrinsic to UTe2 and quite sensitive to the H angle, and that its SC character is different from that in the low-H SC (LHSC) state. The dominant spin component of the spin-triplet pair is along the a axis in the LHSC state but is changed in the HHSC state along the b axis. Our results indicate that H-induced multiple SC states originate from the remaining spin degrees of freedom.

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supporting

confidence: 87%

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Kinjo¹,

Fujibayashi²,

Kitagawa³

et al. 2022

Preprint

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“…The first hypothesis would be opposite to common belief that UTe 2 is a p-wave spin-triplet superconductor, and it requires some exchange field mechanism like in paramagnetic Chevrel phases [54] to account for such a large effective gyromagnetic ratio. The second one is well supported by the recent Knight-shift measurements [19], yielding essentially no change of the Knight-shift along the a axis, and only minute changes along the b and c axes. It should be stressed here that NMR measurements are performed at fixed field.…”

Section: Normal Phase Specific-heatsupporting

confidence: 70%

“…It is more reasonable as regards values of the gyromagnetic factor, and it is well supported by other experiments. Following the NMR results [19], we also assumed a negligible paramagnetic limitation in the (LF) phase along the b and c axes. We used the same strong-coupling model as in [20,49], which mimics H c2 for a spin-triplet superconductor with a calculation for an s-wave superconductor with g = 0.…”

Section: Normal Phase Specific-heatmentioning

confidence: 99%

“…Nevertheless, neutron scattering studies only detected antiferromagnetic correlations [17], and theories have also predicted the observed E 2u state by antiferromagnetic fluctuations [18]. In UTe 2 , ev-idence for spin-triplet pairing comes from NMR Knightshift measurements, recently performed along all crystallographic axes [19], and from the strong violation of the paramagnetic limit by the superconducting upper critical field H c2 [1,5,[20][21][22]. Several theoretical works have proposed models for the pairing with or without ferromagnetic correlations, and for the different possible symmetry states under fields of pressure [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Field-induced tuning of the pairing state in a superconductor

Rosuel¹,

Marcenat²,

Knebel³

et al. 2022

Preprint

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The recently discovered superconductor UTe2 with a Tc between 1.5 K and 2 K, has attracted much attention due to indications of spin-triplet and topological superconductivity. Its properties under magnetic field are also remarkable, with field-reinforced and field-induced superconducting phases. Here, we report the first complete thermodynamic determination of the phase diagram for fields applied along the three crystallographic directions. Measurements were performed up to 36 T along the hard b axis in order to follow the superconducting transition up to the metamagnetic transition at Hm = 34.75 T. They demonstrate the existence of a phase transition line within the superconducting phase, and drastic differences occurring between these two phases. Detailed analysis supports a different spin state between the two phases, possibly a spin-triplet to spin-singlet transition.

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“…A spin-triplet nature of superconducting pairing has been proposed for this compound initially presented as a nearly-ferromagnetic system. Spin-triplet superconductivity in UTe 2 is supported by the observation of a critical superconducting field exceeding the Pauli limitation expected for the three crystallographic directions 2,5 and by nuclear-magneticresonance (NMR) knight-shift experiments made in the superconducting state 2,6,7 . Superconductivity is reinforced near a first-order metamagnetic transition induced at a magnetic field µ 0 H m = 35 T applied along the hard direction b [2,5,8,9,10].…”

Section: Introductionmentioning

confidence: 96%

Anisotropic signatures of the electronic correlations in the electrical resistivity of UTe$_2$

Thebault,

Knafo,

Vališka

et al. 2022

Preprint

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Multiple unconventional superconducting phases are suspected to be driven by magnetic fluctuations in the heavy-fermion paramagnet UTe2, and a challenge is to identify the signatures of the electronic correlations, including the magnetic fluctuations, in the bulk physical quantities. Here, we investigate thoroughly the anisotropy of the electrical resistivity of UTe2 under intense magnetic fields up to 70 T, for different electrical-current and magnetic-field configurations. Two characteristic temperatures and an anisotropic low-temperature Fermi-liquid-like coefficient A, controlled by the electronic correlations, are extracted. Their critical behavior near the metamagnetic transition induced at µ0Hm 35 T for H b is characterized. Anisotropic scattering processes are evidenced and magnetic fluctuations are proposed to contribute, via a Kondo hybridization, to the electrical resistivity. Our work appeals for a microscopic modeling of the anisotropic contributions to the electrical resistivity as a milestone for understanding magnetically-mediated superconductivity in UTe2.

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Superconducting Order Parameter in UTe₂ Determined by Knight Shift Measurement

Cited by 49 publications

References 24 publications

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Field-induced tuning of the pairing state in a superconductor

Anisotropic signatures of the electronic correlations in the electrical resistivity of UTe$_2$

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Superconducting Order Parameter in UTe2 Determined by Knight Shift Measurement

Cited by 49 publications

References 24 publications

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Magnetic field-induced transition with spin rotation in the superconducting phase of UTe2

Field-induced tuning of the pairing state in a superconductor

Anisotropic signatures of the electronic correlations in the electrical resistivity of UTe$_2$

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Product

Resources

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Superconducting Order Parameter in UTe₂ Determined by Knight Shift Measurement