UTe2 has attracted considerable attention because of its exotic superconducting properties, including field-reentrant superconductivity and multiple superconducting phases. It is a heavy-fermion paramagnet with a superconducting transition at 1.5–2.1 K. The upper critical field far exceeds the Pauli limit for all field directions, providing strong evidence for spin-triplet pairing. For magnetic fields along the hard-magnetization b-axis, field-reentrant superconductivity emerges at high fields and persists up to the metamagnetic transition at Hm~35 T. When the field is tilted toward the c-axis, superconductivity reappears above Hm and survives up to 70 T. Pressure studies further reveal multiple superconducting phases before superconductivity is replaced by antiferromagnetism above 1.45 GPa.
In this talk, I will review the current understanding of UTe2, focusing on our recent high-field experiments. I will discuss field-reentrant superconductivity in comparison with ferromagnetic superconductors and present recent quantum-oscillation results that provide insight into possible Fermi-surface instabilities and the unresolved pairing symmetry.