Superconductivity in materials without inversion symmetry (NCS) in the respective crystal structures occurs in the presence of an antisymmetric pin-orbit coupling as a consequence of an emerging electric field gradient. The superconducting condensate is then a superposition of spin-singlet and spin-triplet Cooper pairs. This scenario accounts for various experimental findings such as nodes in the superconducting gap or extremely large upper critical magnetic fields found in superconductors like CePt₃Si or CeRhSi₃.
Spin-triplet pairing can occur in a NCS environment in spite of Anderson's theorem that spin-triplet pairing requires a crystal structure that exhibits inversion symmetry. A central issue that arises when debating physical properties of NCS superconductors pertains the role of strong correlations among electrons.