A pinning model and universal pinning regimes in YBa2Cu 3O7 superconducting films
A model for vortex pinning at boundaries with modulated pinning potentials is developed for high-quality YBa2Cu3O7 superconducting films and multilayers. This model accurately describes the experimentally obtained Jc(Ba) behavior in different films over the entire field and temperature (T) ranges. Deviations are observed at high fields and temperatures due to the thermally activated depinning which is not accounted for by the model. A supplementary “model-free” analysis of the temperature dependent Jc curves leads to the four regions in the field-temperature phase diagram which are attributable to the well-known pinning regimes of collective pinning theory. The results obtained indicate the universality of the pinning model developed, which incorporates the universal pinning regimes and the ability to describe Jc(Ba,T) dependences.