Odd-Parity Superconductivity with Parallel Spin Pairing inUPt3: Evidence from195PtKnight Shift Study

The temperature dependence of the {sup 195}Pt Knight shift, {ital K}, for the high quality single crystal UPt{sub 3} has been measured down to {ital T}=28 mK in applied magnetic fields parallel and perpendicular to the hexagonal {ital c} axis. No change of {ital K}{close_quote}s has been found across the superconducting transition temperature {ital T}{sub {ital c}} down to 28mK regardless of the crystal directions and independent of the superconducting multiphases. It is demonstrated that UPt{sub 3} is the odd-parity superconductor with {ital parallel} {ital spin} {ital pairing} following the direction of the magnetic field in a range of 4.4{endash}15.6kOe without an appreciable pinning of the order parameter to the lattice. {copyright} {ital 1996 The American Physical Society.}