Effects of the surface boundary on the magnetization process in type-II superconductors

Computer simulations, based on the time-dependent Ginzburg-Landau equation of the magnetization process of type-II superconductors in a magnetic field are presented. It is shown how the magnetic flux penetrates into and goes out of the superconductor through the surface boundary, i.e., the superconductor-insulator interface. By examining the hysteresis curve of the magnetization, the surface pinning field is derived. The flux distribution and its time development in the superconductor are calculated when the magnetic field is increased or decreased. We also study the surface and edge states of the type-II superconductor above the upper critical field.