Possible metamagnetism in the high-pressure tetragonal phase of UTe 2

A structural orthorhombic-to-tetragonal phase transition was recently discovered in the heavy-fermion compound UTe 2 at a pressure p * <^>-center dot 3 - 8 GPa [Honda et al. , J. Phys. Soc. Jpn. 92 , 044702 (2023); Huston et al. , Phys. Rev. Mater. 6 , 114801(2022)]. In the high -pressure tetragonal phase, a phase transition at T x = 235 K and a superconducting transition at T sc = 2 K have been revealed. In this work we present an electrical-resistivity study of UTe 2 in pulsed magnetic fields up to mu 0 H = 58 T combined with pressures up to p = 6 GPa. The field was applied in a direction tilted by 30 degrees from b to c in the orthogonal structure, which is identified as the direction c ' of the tetragonal structure. In the tetragonal phase, the presence of superconductivity is confirmed and signatures of metamagnetic transitions are observed at the fields mu 0 H x 1 = 24 T and mu 0 H x 2 = 34 T and temperatures smaller than T x . We discuss the effects of uniaxial pressure, and we propose that a magnetic ordering drives the transition at T x .