We report the measurements of the $^{ 29}$Si Knight shift $^{ 29}K$ on the noncentrosymmetric heavy-fermion compound CePt$_{ 3}$Si in which antiferromagnetism (AFM) with $T_{ \rm N}=2.2$ K coexists with superconductivity (SC) with $T_{ c}=0.75$ K. Its spin part $^{ 29}K_{ \rm s}$, which is deduced to be $K_{ \rm s}^{ c}\ge 0.11$ and 0.16% at respective magnetic fields $H=2.0061$ and 0.8671 T, does not decrease across the superconducting transition temperature $T_{ c}$ for the field along the c-axis. The temperature dependence of nuclear spin-lattice relaxation of $^{ 195}$Pt below $T_{ c}$ has been accounted for by a Cooper pairing model with a two-component order parameter composed of spin-singlet and spin-triplet pairing components. From this result, it is shown that the Knight-shift data are consistent with the occurrence of the two-component order parameter for CePt$_{ 3}$Si.
Categories: cond-mat.supr-con cond-mat.str-el