Giant vortex states in type I superconductors simulated by Ginzburg-Landau equations

Abstract

The quantization of magnetic flux in superconductors is usually seen as vortices penetrating the sample. While vortices are unstable in bulk type I superconductors, restricting the superconductor causes a variety of vortex structures to appear. We present a systematic study of giant vortex states in type I superconductors obtained by numerically solving the Ginzburg-Landau equations. The size of the vortices is seen to increase with decreasing film thickness. In type I superconductors, giant vortices appear at intermediate thicknesses but they do not form a well-defined vortex lattice. In the thinnest type I films, singly quantized vortices seem to be stabilized by the geometry of the sample instead of an increase in the effective Ginzburg-Landau parameter.