Rare earth ion size effects and enhanced critical current densities in Y2∕3Sm1∕3Ba2Cu3O7−x coated conductors

The influence of rare earth (RE) ion size on critical current density (Jc) in epitaxial films of superconducting REBa2Cu3O7−x was studied, where RE is the mixture of two or three rare earth ions. No systematic dependence of Jc on RE ion size was found. However, strongly enhanced critical current densities (Jc’s) were found for the composition Y2∕3Sm1∕3Ba2Cu3O7−x (YSmBCO). In ∼1-μm-thick films, Jc’s as high as 4.7×106Acm−2 (75.5K,0T) and 11×104Acm−2 (75.5K,5T) were obtained on single crystals and 6×104Acm−2 (75.5K,5T) on buffered metal. The values are up to a factor of 3 higher than for comparative YBCO samples.