Odd-frequency pairings in a non-centrosymmetric system

We study possible pairing symmetries of non-centrosymmetric superconductors in the Hubbard model with the Rashba-type spin–orbit interaction (RSOI). Because of the breakdown of space inversion symmetry due to RSOI, a mixture of pairing states with different symmetries can emerge. We find that the RSOI mixes not only the spin-singlet even-parity pairing and spin-triplet odd-parity pairings with even-frequency symmetry, but it also mixes the spin-singlet odd-parity pairing and spin-triplet even-parity pairings with odd-frequency symmetry.