Current-Voltage Characteristics of YBa 2 Cu 3 O y /La 0.7 Ca 0.3 MnO z /YBa 2 Cu 3 O y Trilayered-Type Junctions

YBa 2 Cu 3 O y (superconductor)/La 0.7 Ca 0.3 MnO z (magnetic material)/YBa 2 Cu 3 O y (superconductor) trilayered-type junctions were prepared on MgO(100) single-crystal substrates, and the current-voltage characteristics were examined. The top and bottom YBa 2 Cu 3 O y layers were 200 nm thick, and the La 0.7 Ca 0.3 MnO z layer was 20, 30, 50 or 100 nm thick. A supercurrent was observed through all the La 0.7 Ca 0.3 MnO z layers, even the thickest one. Further investigation showed that a supercurrent could he observed through the 500-nm barrier layer.