Spin Triplet Superconductivity and Spin–Orbit Coupling in CePt3Si

We show that the two superconducting transition temperatures observed in CePt 3 Si [higher transition temperature (0.75 K) in as-cast samples and lower transition temperature (0.45 K) in annealed samples and single crystals] are due to the pair breaking effect of spin–orbit coupling. By assuming that the local electric field due to the lack of inversion symmetry is large in the annealed samples and very small in the as-cast samples, the difference in transition temperature is explained by the order parameter of the triplet superconductivity as d ( k )∝( k z ,0,0) or (0, k z ,0). This d vector is caused by interplane coupling and is consistent with the constant Knight shift in the superconducting state in any direction of the magnetic field. The possibility of obtaining Cooper pairs with a finite total momentum (Fulde–Ferrell–Larkin–Ovchinnikov state) caused by spin–orbit coupling is studied.