MAGNETIC RESHUFFLING AND FEEDBACK ON SUPERCONDUCTIVITY IN UTe₂ UNDER PRESSURE

Michal Vališka, CEA-Grenoble and Charles University Prague, William Knafo, LNCMI Toulouse and Daniel Braithwaite, CEA-Grenoble.

The discovery of superconductivity in the heavy-fermion paramagnet UTe₂ has attracted a lot of attention, particularly due to the reinforcement of superconductivity near quantum phase transitions induced by magnetic field and/or pressure. In this system, hydrostatic pressure induces an enhancement of the superconducting transition temperature by a factor of two, reaching about 3 K. The effect of magnetic field on the ambient-pressure superconductivity is also very unusual, with the superconducting critical field exceeding 60 T for certain field directions. Here, we investigated the electrical resistivity of UTe₂ under pressures up to 3 GPa and pulsed magnetic fields up to 58 T along the hard magnetic crystallographic b and c direction. We constructed three-dimensional phase diagrams (figure) and showed that the application of pressure and magnetic field leads to extremely complex phases in UTe₂ with a complete reshuffling of the magnetic anisotropy and associated strong effects on superconductivity. Near the critical pressure, a field enhancement of superconductivity coincides with a boost of the effective mass related to the collapse of metamagnetic and critical fields at the boundaries of the correlated paramagnetic regime and magnetically ordered phase, respectively. Beyond the critical pressure, field-induced transitions precede the destruction of the magnetically ordered phase, suggesting an antiferromagnetic nature. By providing new elements about the interplay between magnetism and superconductivity, our paper appeals for microscopic theories describing the anisotropic properties of UTe2 under pressure and magnetic field.

Figure: Three-dimensional (p,H,T) phase diagrams and evolution of the Fermi-liquid coefficient A in the low-temperature (p,H) planes of UTe₂ in magnetic fields applied along b and c.

Magnetic reshuffling and feedback on superconductivity in UTe₂ under pressure, M. Vališka, W. Knafo, G. Knebel, G. Lapertot, D. Aoki, and D. Braithwaite, Phys. Rev. B 104, 214507 (2021). https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.214507

Contact: william.knafo@lncmi.cnrs.fr , michal.valiska@gmail.com , daniel.braithwaite@cea.fr