Reinforcement of pinning by surface magnetic microparticles in high-Tc superconductors

A reinforcement of pinning in high-T-c superconducting materials by surface magnetic microparticles obtained by ion implantation is observed. Measurements are made by the method of magnetically modulated microwave absorption. In single crystals of Bi2Sr2CaCu2O8 an ensemble of magnetic particles is formed directly in a subsurface layer of the superconductor by the implantation of Fe+ ions followed by annealing. In experiments with YBa2Cu3O7 the magnetic microparticles of iron were formed individually in SiO2 films which were then applied to the surface of a thin film of YBa2Cu3O7, and measurements were made on the composite structure. In both cases reinforcement of the pinning is observed. In the limits of the chosen implantation regimes the pinning effect becomes stronger with increasing fluence of implanted iron atoms. (C) 2002 American Institute of Physics.