Critical current density of YBCO films with different configurations of columnar defects in longitudinal magnetic field

29th International Symposium on Superconductivity

Sueyoshi, T.^1 ; Iwanaga, Y.^1 ; Kai, T.^1 ; Izumi, T.^1 ; Fujiyoshi, T.^1 ; Ishikawa, N.^2

Department of Computer Science and Electrical Engineering, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto

860-8555, Japan^1

Japan Atomic Energy Agency (JAEA), Tokai-mura, Ibaraki

319-1195, Japan^2

关键词: Degradation effect;    Irradiated films;    Irradiation angles;    Longitudinal magnetic fields;    Magnetic field dependences;    Parallel configuration;    Transport currents;    YBa2Cu3Oy thin films;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012043/pdf
DOI  :  10.1088/1742-6596/871/1/012043

来源: IOP

【 摘 要 】

Critical current density (Jc) properties in longitudinal magnetic fields were investigated for YBa2Cu3Oythin films with columnar defects (CDs), where different configurations of CDs were systematically installed into the films by using heavy-ion irradiation: a parallel configuration of CDs aligned along the c-axis and two bimodal splay configurations composed of CDs crossing at ± θirelative to the c-axis, where the splay plane defined by the two irradiation angles is perpendicular or parallel to the transport current direction. The unirradiated film under the longitudinal magnetic field shows a Jcpeak in the magnetic field dependence of Jc, which is 1.1 times higher than the self-field Jc. For the irradiated films with the parallel CD configuration, on the other hand, the Jcis lower than that for the unirradiated film in all magnetic fields and the value of Jcdecreases with increasing CD density. Such degradation effect by CDs under longitudinal magnetic field was observed even for the bimodal splay configurations. These results are attributed to local meandering of current flow induced by CDs extending through the film thickness, which deteriorates the force-free condition.