Superconductivity of UPt3 studied by μ+SR and neutron scattering (abstract)

The magnetic field penetration depth λ in single-crystalline UPt3 has been measured by muon spin relaxation ( μ+SR). The temperature dependence of λ−2 is nonexponential and anisotropic decreasing from its T=0 value proportional to T when measured perpendicular to the c axis but with a higher-power ∥c. Our data can be accounted for in detail by a superconducting gap with a line of nodes in the basal plane and axial point nodes. By neutron scattering we furthermore show that the antiferromagnetic order parameter of UPt3 is perturbed by the development of superconductivity. We discuss the implications of these results on the symmetry of the superconducting states of UPt3.