Nonunitary spin-triplet superconductors in Zeeman magnetic field

We study spin-triplet superconductivity, including the case of non-unitary pairing, in the presence of a Zeeman magnetic field. By exactly diagonalizing the Bogoliubov–de Gennes Hamiltonian, we derive the corresponding gap equation and obtain general expressions for the quasiparticle spectrum and spin magnetization. These results are valid for arbitrary magnetic field strengths and temperatures. We analyze in detail the nonlinear spin susceptibility and the evolution of the superconducting gap and transition temperature under magnetic fields, emphasizing the distinctions between unitary and non-unitary pairing. Our findings are broadly applicable to a wide range of materials, including systems with both weak and strong spin–orbit coupling. We further discuss possible implications for 4Hb-TaS₂ and PrOs₄Sb₁₂