Study of the effect of intrinsic and induced defects on the I-V characteristics of YBCO films

The current-voltage (I-V) characteristics of YBCO films in zero applied mag netic field were investigated. Different conditions of fabrication have bee n considered in order to face with different structural defect configuratio ns, The measurements were performed in a wide range of temperature, in the regime of thermal activation motion of magnetic vortices. The current-depen dent activation energy for dissipative behavior was evaluated, and a correl ation to the structural sample configuration was attempted. The results wer e compared to those obtained in Au+ ion irradiated samples, where a regular distribution of artificial columnar defects is added to the background sup erconductor crystal defects. Two levels of irradiation were considered for the same sample. (C) 2000 Elsevier Science B.V. All rights reserved.