Overcoming optimization constraint for J c by hybrid pinning in YBa2Cu3O7 films containing nanorods

Abstract Critical current density ( J c ) in YBa 2 Cu 3 O 7 films are improved by nanorods. J c increases with increasing the nanorod content up to an optimum content, and decreases after exhibiting a maximum due to degradation of the nanorod structure. To overcome this optimization constraint, hybrid pinning consisting of multiple types of pinning centers was investigated. In the present study, Y 2 O 3 nanoparticles were additionally introduced into the YBa 2 Cu 3 O 7 films containing high density BaHfO 3 nanorods to increase the effective matching field. As a result, the global pinning force maximum was shifted to high magnetic field, and the J c was improved especially in high magnetic field. Thus, even in the case that the J c improvement in the YBa 2 Cu 3 O 7 + BaHfO 3 was difficult by increasing the nanorod content, the Y 2 O 3 addition successfully improved the J c . This demonstrates that the hybrid pinning can overcome the optimization constraint for J c in the YBa 2 Cu 3 O 7 films containing nanorods.