Temperature dependence of the self-field critical current densities and flux pinning in YBa2Cu3O7-d thin films containing nanoprecipitates

The temperature dependence of the self-field and in-field critical current densities J(c)(T) was investigated in YBa2Cu3O7-delta thin films containing a high density of nanoprecipitates. The self-field J(c)(T) and in-field J(c)(T) were both approximated by J(c)(T) ~ (1 - T/T-c)(m) (1 + T/T-c)(2), where the index m was mostly 2.0-2.6 in moderate magnetic fields (mu H-0 = 0.5-1 T, // c-axis), but m was smaller (1.5-1.8) in self-fields. This phenomenon can be explained by the assumption that the self-field J(c) is determined by the flux pinning by relatively large nano-precipitates, which is supported by simple theoretical calculations of the elementary pinning force f(p) due to the core pinning interaction. The self-field J(c) is estimated to be proportional to 1/lambda(3), where lambda is the penetration depth. This relationship can successfully explain the previously observed inverse correlation between the self-field J(c) and the surface resistance R-s that is supposed to be proportional to lambda(3).

Automated summary

The temperature dependence of the self-field and in-field critical current densities J(c)(T) was studied in YBa2Cu3O7-delta thin films with a high density of nanoprecipitates. The self-field J(c) is mainly influenced by flux pinning from relatively large nano-precipitates, while the in-field J(c) is affected by other factors.