RESUMEN
We demonstrate that the presence of edges in a superconducting film made of a type-I/type-II bilayer stabilizes type-II/type-I hybrid (inter-type) flux patterns, as vortex clusters, chains, and gel phase. These patterns are very sensitive to primary parameters such as applied magnetic field, layer coupling, and temperature. Thus, the magnetization versus temperature curves, M(T), for many values of coupling were used to estimate the strength of the layer couplings, and also as a guide for obtaining sequentially the flux patterns. We also show that the effect of the borders on the unrestricted states is to shift them to states of higher density, since they introduce extra compression on the vortex matter. For a low layer coupling regime, we observe an unusual magnetic response where few partial vortices (partial in a sense they miss the contribution of the type I part), repelling each other and bounded to the surfaces, populate one layer leaving the other empty. We expect that the predicted flux configurations can stimulate experimentalists in trying to observe them by direct imaging techniques.
RESUMEN
We show how the inclusion of a structural defect of determined geometry controls the vortex state in a square superconducting sample in the presence of an external magnetic field and a dc current. We simulated the defects by using the deformation parameter τ ( x , y ) , solving the non-lineal time-dependent Ginzburg-Landau equations and using the link variable method, for four different geometries as possible options for the storage vortex, simulating the behavior of a capacitor. We found an exponential dependence of the current in which the first vortex penetrates the sample J â c as a function of the area of a square central defect in the sample. We also show the effect of the defects and the transport current on the magnetization, magnetic susceptibility, vorticity, and magnetic field at the first vortex entry into the sample H 1 and the density of the superconducting electrons.