Several unconventional superconducting phases have been discovered close to a metamagnetic transition in the heavy-fermion compound ${\mathrm{UTe}}_2$. Although suspected to be of magnetic nature, the mechanisms stabilizing these superconducting phases remain mysterious. Here, we present electrical-resistivity measurements on ${\mathrm{UTe}}_2$, 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 ${30}^{\circ }\text{–}{40}^{\circ }$ 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 ${\mu }_0{H}_m\gtrsim 40\mathrm{T}$. 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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• High magnetic fields
• Magnetism
• Spin fluctuations
• Superconductivity
• Heavy-fermion systems
• Unconventional superconductors