The low- and high-field superconducting phases of UTe₂

Recent NMR and calorimetric experiments have observed that UTe₂ exhibits a transition between two distinct superconducting phases as a function of magnetic field strength for a field applied along the crystalline b-axis. To determine the nature of these phases, we employ microscopic model Hamiltonians inspired by density functional theory. We apply a mean field theory to study the symmetries and properties of these low- and high-field phases.