Fermi-Liquid Renormalization in the Superconducting State of UBe sub (13)

The specific heat in the mixed phase of superconducting UBe sub (13) is observed to vary as the square of the applied magnetic field. This is shown to imply a Fermi-liquid-type suppression of the exchange enhancement as the superconducting gap opens, similar to that seen in 3 sub (He). Consistent with this effect is the observed non-monotonic temperature dependence of the Maki parameter, kappa sub 2, which is related to the Pauli susceptibility.