Geometric and compositional factors on critical current density in YBa2Cu3O7−δ films containing nanorods

Critical current density (Jc) was investigated in YBa2Cu3O7−δ films containing nanorods prepared with various nanorod materials, with variation of nanorod content, substrate temperature, and oxidization condition. Three types of compositional situation were realized: films containing strain induced oxygen vacancies; fully oxidized films containing cation compositional deviation; and oxygen deficient films. Normalized Jc−B behavior was determined via the matching field, which is a geometric factor, regardless of the compositional details. A Jc−critical temperature (Tc) relation depending on distribution and fraction of compositional deviation (cation compositional deviation and strain induced oxygen vacancies) was found: the Jc values decreased with decreasing Tc due to the effect of Tc on nanorod pinning strength in the fully oxidized films; Jc decreased with decreasing oxygen pressure in the film cooling process after film deposition in spite of Tc remaining almost the same, due to reduction of the effective area for current flow in the oxygen deficient films. Thus, a Jc landscape based on geometric and compositional factors was obtained. The study highlights the importance of the Jc−Tc analysis in the understanding of Jc in YBa2Cu3O7−δ films containing nanorods.