POSSIBLE METAMAGNETISM IN THE HIGHPRESSURE TETRAGONAL PHASE OF UTe₂

Tristan Thebault, William Knafo, LNCMI Toulouse, Daniel Braithwaite, Gérard Lapertot, Georg Knebel, CEA-Grenoble, and Dai Aoki, Tohoku University.

The interplay between magnetism and unconventional superconductivity in UTe₂ was extensively studied in the past few years. Multiple superconducting phases were found to be induced near to a metamagnetic transition under magnetic field either at ambient pressure or combined with pressure. A structural orthorhombic-to-tetragonal phase transition was also recently discovered at a pressure p* ≈ 3.5 – 8 GPa.

In this work, we have investigated the electrical resistivity of UTe₂ in pulsed magnetic fields up to 58 T combined with pressures up to 6 GPa. The field was applied in a direction tilted by 30° from b to c in the low-pressure orthorhombic structure, which is identified as the direction c’ of the high-pressure tetragonal structure. In the tetragonal phase, possible metamagnetic transitions are observed at μ₀ H_x1 = 24 T and μ₀ H_x2 = 34 T. They disappear at temperatures higher than T_x = 235 K, at which an electronic phase transition is reported from the zero-field resistivity. We propose that magnetic ordering drives the transition at T_x and that magnetic-moment reorientations are induced at H_x1 and H_x2. Further challenges will be to determine the nature of the electronic phase stabilized below T_x and to understand how the properties of the tetragonal phase may be related to those of the orthorhombic phase.

Figure: (a) Pressure-magnetic-field phase diagram of UTe₂. (b) Evolution of the electrical resistivity under magnetic field for temperatures between 1.4 and 220 K at 4.9 GPa. Three dimensional views of (c) the orthorhombic and (d) the tetragonal phase.

Possible metamagnetism in the highpressure tetragonal phase of UTe₂, T. Thebault, D. Braithwaite, G. Lapertot, D. Aoki, G. Knebel, and W. Knafo, Phys. Rev. B 109, 214420 (2024).

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.214420

Contact: tristan.thebault@lncmi.cnrs.fr, william.knafo@lncmi.cnrs.fr, daniel.braithwaite@cea.fr