Flux Pinning by Columnar Defects Along a-axis in a-axis Oriented YBCO Thin Films

• Published in: IEEE transactions on applied superconductivity 2019-08, Vol.29 (5), p.1-4
• Main Authors: Sueyoshi, Tetsuro, Iwanaga, Yasuya, Fujiyoshi, Takanori, Takai, Yosuke, Muta, Mitsuhiro, Mukaida, Masashi, Ichinose, Ataru, Ishikawa, Norito
• Format: Article
• Language: English
• Subjects: Anisotropic magnetoresistance; anisotropy; columnar defects; critical current; Critical current density; Critical current density (superconductivity); Defects; Dependence; Flux pinning; High-<inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX"> {T}_{\text{c}}</tex-math> </inline-formula> superconductors; Ion irradiation; Magnetic fields; Radiation effects; Substrates; Thin films; Trapping; Yttrium barium copper oxide
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2019.2896473

Columnar defects (CDs) along a-axis were installed into an in-plane aligned a-axis-oriented YBa 2 Cu 3 O y film by using heavy-ion irradiation, in order to clarify the influence of CDs on flux pinning properties around B || ab. The critical current density J c at B || c significantly decreases after the irradiation, since the CDs act as a channel for flux creep along their length. The magnetic field dependence of J c at B || ab, on the other hand, is weakened by the introduction of CDs. This means that the CDs can trap flux lines at B || ab, whereas naturally growth defects working as effective ab-correlated PCs exist. The trapping angle of CDs along the a-axis is extremely narrow (~5.8°) in comparison with CDs along the c-axis and is roughly coincides with other ab-correlated PCs. The small trapping angle of CDs along the a-axis is attributed to strong line tension energy of flux lines with elliptical core around B || ab.