Metamagnetism in the high-pressure tetragonal phase of UTe${}_2$

Abstract

A structural orthorhombic-to-tetragonal phase transition was recently discovered in the heavy-fermion compound UTe${}_2$ at a pressure $p^{\ast }\simeq 3-8$~GPa [Honda \textit{et al.}, J. Phys. Soc. Jpn. \textbf{92}, 044702 (2023); Huston \textit{et al.}, Phys. Rev. Mat. \textbf{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 $\hat{I}{¼}_{0}H=58$~T combined with pressures up to $p$ = 6 GPa. The field was applied in a direction tilted by 30~${}^{\circ }$~from \textbf{b} to \textbf{c} in the orthogonal structure, which is identified as the direction \textbf{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 $\hat{I}{¼}_0{H}_{x1}=24$~T and $\hat{I}{¼}_0{H}_{x2}=34$~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 $T_x$.

13 pages, 11 figures, Supplemental Material: 18 pages, 17 figures