Fulde–Ferrell–Larkin–Ovchinnikov state due to antisymmetric spin–orbit coupling in the noncentrosymmetric superconductor CePt3Si

Abstract

When the inversion symmetry is broken, the spin–orbit coupling reduces the superconducting transition temperature of some types of spin triplet superconductivity, which is similar to the case that magnetic field weakens the spin singlet superconductivity due to Zeeman splitting. It is well known that Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state of spin singlet superconductivity is realized near the Pauli limit (or Chandrasekhar–Clogston limit). In the FFLO state the amplitude of the order parameter is not uniform in space. In this paper, we study the FFLO state of the spin triplet superconductivity due to the spin–orbit coupling with no external magnetic field. Although the FFLO state is not realized in the simple model with spherical Fermi surface, it will be stabilized if the nesting condition of the Fermi surface is favorable for the FFLO state. We discuss the possibility of FFLO state in CePt3Si in the absence of external magnetic field.