Unconventional singlet-triplet superconductivity

Abstract

Have you been lying awake wondering what symmetries determine whether a superconductor is spin-singlet, triplet, or both? We show that if one supplies additional degrees of freedom to BCS theory, spin-singlet can coexist with spin-triplet superconductivity. We guide the reader to the most general superconducting state using symmetry arguments. If both singlet and triplet pairing channels act, a magnetic field can convert between spin-singlet and triplet states. Two possible singlet-triplet superconductors candidates are: CeRh2As2 and bilayer-NbSe2.