Multiple Superconducting Phases under Pressure in Spin-Triplet Superconductor UTe₂

Abstract

We report recent experimental results on multiple superconducting phases in the spin-triplet superconductor UTe₂, revealed by ac calorimetry under pressure. When a small hydrostatic pressure is applied, the superconducting transition splits into two distinct temperatures, indicating the emergence of multiple superconducting phases. Furthermore, magnetic fields applied along either the easy or hard magnetization axis induce a rich variety of superconducting phases, reflecting the spin and orbital degrees of freedom inherent to the spin-triplet state.