Flux trapping in a superconducting thin film as revealed by simulations and scanning superconducting quantum interference device microscope observations

Penetration of magnetic fluxes into a superconducting thin film that contai ned holes was studied for fast and slow cooling rates (0.18 and 0.009 K/s, respectively) under an ambient magnetic field of about 3 mu T. By using a s canning superconducting quantum interference device microscope, we observed trapped magnetic fluxes both inside and outside of holes prepared in a sup erconducting film. The trapped fluxes outside the holes appeared in a regul ar arrangement when the superconducting film was cooled at the slow rate. O bserved arrangements of the trapped fluxes were compared with a simulation that was based on a theoretical model that considered the surface barrier a nd the interaction among fluxes. The simulation explained well the observed arrangements of magnetic fluxes. (C) 2000 American Institute of Physics. [ S0003-6951(00)04537-X].