Creation of strong pinning sites by x-ray irradiation for Gd1Ba2Cu3O7−x superconducting thin films

Abstract
A large enhancement of critical current density with the small rate of flux creep was realized by x-ray irradiation before the oxygen annealing for Gd1Ba2Cu3O7−x superconducting thin films. The significantly increased magnetization showed both the temperature independence and the small magnetic relaxation. The activation energy estimated by the flux creep model increased from 0.1 to 0.25 eV with the x-ray irradiation treatment.