Multiband superconductivity in CePt3Si without inversion symmetry:195Pt-NMR study

We report on novel superconducting characteristics of the heavy fermion (HF) superconductor CePt3Si without inversion symmetry through 195Pt-NMR study on a high quality single crystal with Tc = 0.46 K that is lower than Tc ~ 0.75 K for polycrystals. The observation of short and long components in a nuclear relaxation time T1 has revealed the presence of inhomogeneities of superconducting characteristics even in a single crystal. By discriminating the clean domain from the disordered domains, we show that the intrinsic superconducting characteristics inherent to CePt3Si can be understood in terms of the unconventional strong-coupling state with a line-node gap below Tc = 0.46 K. Furthermore, it was found that in some disordered domains that are inevitably contained in regardless of polycrystals or single crystals a conventional BCS s-wave superconducting state is realized below Tc ~ 0.75 K. We propose that these unusual superconducting and magnetic characteristics of CePt3Si can be described by a multiband model on the basis of the experimental facts.