195Pt Knight shift study of single crystal UPt3—evidence for odd-parity pairing

The195Pt Knight shift of the high quality single crystal UPt3 measured down toT=28 mK have revealed no change acrossTc regardless of the applied field directions and of the superconducting multiphases. An estimation of the spin part from theT linear specific heat has ensured no variation of the dominant spin part of the measured Knight shift belowTc as well as its estimation by the subtraction of the Van Vleck part from theT dependence of the Knight shift in the highT region reported in the previous paper. It is reinforced that UPt3 is the odd-parity superconductor with equal spin pairing and the pinning of the order parameter does not take place, suggesting the spin-orbit coupling for the pairing interaction to be not so strong.