Angular Dependence of Critical Current Density in YBCO Films With Columnar Defects Crossing at Widespread Angles

• Published in: IEEE transactions on applied superconductivity Vol. 23; no. 3; p. 8002404
• Main Authors: Sueyoshi, Tetsuro, Furuki, Yuuichi, Tanaka, Eiki, Fujiyoshi, Takanori, Mitsugi, Fumiaki, Ikegami, Tomoaki, Ishikawa, Norito
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2013; Institute of Electrical and Electronics Engineers
• Subjects: Columnar defects; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; critical current density; Critical current density (superconductivity); Critical currents; Cuprates superconductors (high tc and insulating parent compounds); Exact sciences and technology; flux creep; Flux pinning; Ion radiation effects; Magnetic fields; Physical radiation effects, radiation damage; Physics; Properties of type I and type II superconductors; splay effect; Structure of solids and liquids; crystallography; Superconductivity; Vortex lattices ,flux pinning, flux creep; Y-based cuprates; Yttrium barium copper oxide; Cadmium; Critical current density; Radiation effects; Heavy ions; Flux creep; Magnetic field effects; Parallel; splay effect; Cadmium sulfide; Thin films; Flux pinning; Ion irradiation; Calcium nitride; Field orientation; One dimensional model; High-Tc superconductors; Angular variation; Columnar defects; Magnetic fields; Barium Copper Yttrium Oxides Mixed
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2013.2255942

To investigate whether one-dimensional pinning centers can attain the isotropic critical current density (J_{\rm c}) properties, columnar defects (CDs) crossing at widespread angles were installed by heavy-ion irradiation into YBCO thin films. For the sample containing the CDs crossing at 0 ^{\circ} , \pm 30^{\circ} , and \pm 60^{\circ} relative to the c -axis, the plateau-like behavior of J_{\rm c} is realized over a wide range of magnetic field orientations, except for around B\ \Vert\ ab -plane where a dip structure is accompanied by a rapid decline of the J_{\rm c} . For the bimodal splay configuration consisting of CDs crossing at \pm 30^{ \circ} relative to the c -axis, a single peak around the c -axis is observed in the angular denpendece of J_{\rm c} , suggesting the splay effect at B\ \Vert\ c -axis by the crossed CDs. Two parallel families of CDs crossing at \pm 30^{\circ} relative to the ab -plane, on the other hand, bring about not a peak but a dip around B\ \Vert\ ab -plane on the angular dependence of J_{\rm c} . Apparently, the bimodal splay in CD directions relative to the ab -plane does not contribute to the flux pinning around B\ \Vert\ ab -plane, let alone show the splay effect.