Preparation of non-superconducting Pr1.4Ba1.6Cu2.6Ga0.4Oy film for HTS devices

Deposition of Pr1.4Ba1.6Cu2.6Ga0.4Oy (P4G4) thin films as non-superconducting layers in HTS electronic devices having multilayer structures with YBCO-type superconducting layers was studied. Since P4G4 has similarity in crystal structure with YBCO, it may be suitable for constructing multilayer structures containing YBCO. It is also expected that the black-colored P4G4 similar to YBCO can work as a temperature homogenizer for a chip during deposition of the upper layers. c-axis-oriented P4G4 films with flat surfaces were successfully deposited by an off-axis RF magnetron sputtering method. It was found that the insertion of a BaZrO3 buffer layer was effective to fabricate high-quality P4G4 films. As an example of the application of the P4G4, we tried fabricating ramp-edge Josephson junctions with an interface-engineered barrier on a P4G4 layer. Junctions exhibiting resistively shunted-junction-type current-voltage characteristics were successfully obtained