Unconventional flux dynamics in the heavy fermion superconductors UPt3 and UBe13

We have investigated flux creep in single crystals of UPt3 (Hc) and UBe13 (Hc4) in the temperature 5 mK < T < Tc and for magnetic fields H < 0. The relaxation curves for both of these heavy fermion superconductors show novel behaviours, with decay lows which depend strongly on the applied field. At all temperatures, we observe contributions to the decays which seem to arise from different processes with different time dependences, namely logarithmic and stretched exponential. © 1994