In the present work, we have studied the crossover between type I and type II superconductivity on mesoscopic superconducting thin films by numerically solving the 3D Ginzburg-Landau equations. We determined the dependence on temperature of the critical Ginzburg-Landau parameter κ c (d), below which the superconductor behaves as type I for a given thickness d of the film. The effect of the sample dimensions on this crossover was also investigated. Additionally, we report a novel giant vortex configuration with a local minimum of the magnetic field at the centre of the core. Finally, we present certain results suggesting that the vortex-vortex interaction is not monotonic, varying instead from long-range attraction to short-range repulsion.

described the existence of an intermediate type-I superconductor as a consequence of an external surface that affects the well-known classification of superconductors into type I and II. Here we consider the mesoscopic superconductor where the volume-to-area ratio is small and the effects of the external surface are enhanced. By means of the standard Ginzburg-Landau theory, the Tinkham-de Gennes scenario is extended to the mesoscopic type-I superconductor. We find additional features of the transition at the passage from the genuine to the intermediate type I. The latter has two distinct transitions, namely from a paramagnetic to diamagnetic response in descending field, and a quasi-type-II behavior as the critical coupling 1/ √ 2 is approached in ascending field. The intermediate type-I phase proposed here, and its corresponding transitions, reflect intrinsic features of the superconductor and not its geometrical properties.

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Within the framework of the generalized time-dependent Ginzburg–Landau equations, we studied the influence of the magnetic self-field induced by the currents inside a superconducting sample driven by an applied transport current. The numerical simulations of the resistive state of the system show that neither material inhomogeneity nor a normal contact smaller than the sample width are required to produce an inhomogeneous current distribution inside the sample, which leads to the emergence of a kinematic vortex–antivortex pair (vortex street) solution. Further, we discuss the behaviors of the kinematic vortex velocity, the annihilation rates of the supercurrent, and the superconducting order parameters alongside the vortex street solution. We prove that these two latter points explain the characteristics of the resistive state of the system. They are the fundamental basis to describe the peak of the current–resistance characteristic curve and the location where the vortex–antivortex pair is formed.