Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

Abstract

We show that Xe ion irradiation with 80 MeV to GdBa2Cu3Oy-coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles θi relative to the c-axis: continuous CDs with a larger diameter are formed for oblique irradiation at θi = 45°, whereas the same ion beam at a different angle (θi = 0°) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density Jc. In particular, low-energy irradiation defects induce further improvement of Jc in a unique combination of irradiation angles of θi = 0° and ±45°: discontinuous CDs at θi = 0° and crossed CDs at θi = ±45° provide correlated pinning in a wide angular range, which is more strongly enhanced by each other via the pinning of kinks.