Flux penetration, matching effect, and hysteresis in homogeneous superconducting films

The vortex dynamics in homogeneous superconducting films of arbitrary thickness under parallel magnetic field is studied. The strong surface effects in these systems are correctly taken into account by expressing the energy of the in-plane vortices in London background. A Langevin algorithm simulates the flux penetration and dynamical evolution of the vortices as the external field is slowly cycled. The numerical results show that the vortex lattice consists of linear chains of vortices parallel to the film surfaces and undergoes transitions involving formation or destruction of one chain, even for films with thickness greater than the penetration depth. In addition, the magnetization curve is irreversible and presents some similarities with Clem's model for surface pinning.