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arXiv · 2505.09351

Boosted magnetic fluctuations at the onset of superconductivity in UTe$_2$ beyond 40 T

T. Thebault·K. Somesh·G. Lapertot·M. Nardone·A. Zitouni·M. Barragan·J. Béard·J. Billette·F. Lecouturier·S. Tardieu·D. Aoki·G. Knebel·D. Braithwaite·W. Knafo
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Abstract

Several unconventional superconducting phases have been discovered close to a metamagnetic transition in the heavy-fermion compound UTe$_2$. Although suspected to be of magnetic nature, the mechanisms stabilizing these superconducting phases remain mysterious. Here, we present electrical-resistivity measurements on UTe$_2$, with a current $\mathbf{I}\parallel\mathbf{a}$ and under pulsed magnetic fields up to 60~T rotating in the ($\mathbf{b}$,$\mathbf{c}$) plane. We find that the maximum of the Fermi-liquid coefficient $A$ at the metamagnetic transition is enhanced under magnetic fields tilted by $30-40~^\circ$ from $\mathbf{b}$ to $\mathbf{c}$. The enhancement of $A$ coincides with the stabilization of superconductivity in the polarized paramagnetic regime beyond the metamagnetic field $\mu_0H_m\gtrsim40$~T. It is the signature of a boosted quantum-critical magnetic-fluctuation mode probably in play for the mechanism of this superconducting phase. This result appeals for descriptions of the interplay between magnetic-field-induced superconductivity and quantum critical magnetic properties.

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T. Thebault, K. Somesh, G. Lapertot, M. Nardone, A. Zitouni, M. Barragan, J. Béard, J. Billette, F. Lecouturier, S. Tardieu, D. Aoki, G. Knebel, D. Braithwaite, W. Knafo. 2025-05-14. Boosted magnetic fluctuations at the onset of superconductivity in UTe$_2$ beyond 40 T. https://doi.org/10.1103/3hzr-5qcs

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