Heavy ion irradiation and the vortex-glass description of the mixed state in YBa₂Cu₃O₇ epitaxial films

Abstract

We report the behavior of the Ohmic resistivity and the current-dependent dissipation in the mixed state of YBa₂Cu₃O₇ films irradiated with 300 MeV gold ions. The transport in both irradiated and unirradiated states of the samples agrees with the model of a second order phase transition to a vortex glass state. While the zero-field critical temperature and current are reduced by the irradiation, the vortex-glass description of the mixed state remains unchanged up to a dosage of ~9 × 10¹⁰ ions/cm². These results indicate that in these high J_c films the vortex dynamics is controlled by pinning centers distributed at a length scale much shorter than the gold-ion induced defects.