Possible metamagnetism in the high-pressure tetragonal phase of UTe2

A structural orthorhombic-to-tetragonal phase transition was recently discovered in the heavy-fermion compound UTe₂ at a pressure p*3-80.16em0exGPa [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 Tₓ=2350.16em0exK and a superconducting transition at Tsc=20.16em0exK have been revealed. In this work we present an electrical-resistivity study of UTe₂ in pulsed magnetic fields up to μ₀H=580.16em0exT combined with pressures up to p=60.16em0exGPa. The field was applied in a direction tilted by 30^∘ 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 μ₀Hₓ₁=240.16em0exT and μ₀Hₓ₂=340.16em0exT and temperatures smaller than Tₓ. We discuss the effects of uniaxial pressure, and we propose that a magnetic ordering drives the transition at Tₓ.