Angular behaviour of critical current density in YBa2Cu3Oy thin films with crossed columnar defects

作者：Sueyoshi T^*; Sogo T; Nishimura T; Fujiyoshi T; Mitsugi F; Ikegami T; Awaji S; Watanabe K; Ichinose A; Ishikawa N

来源：Superconductor Science and Technology, 2016, 29(6): 065023.

DOI：10.1088/0953-2048/29/6/065023

• critical current density
• flux pinning
• columnar defects
• irradiation

Columnar defects (CDs) were installed into YBa2Cu3Oy thin films at the crossing angle +/-theta(i) relative to the c-axis using 200 MeV Xe ions, in order to clarify the influence of +/-theta(i) on the angular behaviours of critical current density J(c). The width of a J(c) peak occuring at B parallel to c linearly increases with broadening CD-crossing angle, where its shape maintains a single peak in the range of theta(i) <= +/- 25 degrees. The CDs crossing at +/- 45 degrees, on the other hand, drastically change the angular behaviour of J(c) around B parallel to c: the J(c) is equally elevated over the angular region from -45 degrees to 45 degrees in the lower magnetic field, whereas the rapid reduction of the J(c) occurs at B parallel to c with increasing magnetic field, leading to the appearance of double peaks near the irradiation angles, +/- 45 degrees. This crossover phenomenon is attributed to the difference in the pinned states of flux lines between B parallel to c and at the irradiation angles: the CDs crossing at +/- 45 degrees cannot provide the correlated flux pinning along the c-axis, resulting in the uncorrelated pinned state at B parallel to c.

• 出版日期2016-6