A theoretical comparison of the effects of the shape of the pinning potential and a distribution of pinning energies of the apparent pinning energy as measured by magnetic flux creep

In the analysis of magnetic flux creep experiments, it is assumed that, at a given temperature, the pinning energy, which must be overcome by thermal activation, depends on the magnetic induction and its gradient by U(B, Delta B) equivalent to U/sub p/(B)(1-( Delta B/ Delta B/sub max/))/sup n/, where U/sub p/ is the pinning well depth and Delta B/sub max/ corresponds to the critical current density with no thermal activation. Customarily, n is assumed to be unity, and any unusual temperature dependence of U/sub p/ is then ascribed to a distribution of well depths. However, realistic assumptions about the shape of the pinning potential yield 3/2