Magnetic relaxation and activation energies of Xe irradiated DyBa2Cu3O7−δ single crystals

Magnetic-relaxation measurements M(t, T) have been carried out on DyBa2Cu3O7-delta single crystals before and after irradiation with 340 MeV Xe ions. The data are analyzed within the framework of first-order kinetics assuming a distribution of activation energies. The results are in good agreement with the assumption, that the most important pinning mechanism is given by the core interaction of pancake vortices or short sections of a flux line with defects. The irradiation-induced enhancement of the average activation energies of just about 70% can be explained by the broadening of the flux-line core if the flux line is located in the amorphous channels with radius R > xi caused by irradiation damage.