Surface superconductivity and H-c3 in UPt3

Surface superconductivity is studied within Ginzburg-Landau theory for two classes of models for the order parameter of UPt3. The first class assumes two independent one-dimensional order parameters (AB models), while the second assumes a single two-dimensional order parameter (E models). H-c3 is calculated for all cases where the surface normal and magnetic field lie along high-symmetry directions. Assuming specular reflection, it is found that except when H parallel to (c) over cap, the ratio H-c3/H-c2 is either unity or equals its ''s-wave'' value 1.695, although the precise H-c3 vs T curve predicted by the AB and E models differs for various geometries. The results are compared with recent experiments, and predictions are made for future experiments.