RESUMO
To describe the way complexity emerges in seemingly simple systems of nature, requires one to attend to two principal questions: how complex patterns appear spontaneously and why a single system can accommodate their inexhaustible variety. It is commonly assumed the pattern formation phenomenon is related to the competition of several types of interactions with disparate length scales. These multi-scale interactions also lead to frustration within the system, resulting in the existence of a manifold of configurations-patterns with qualitatively distinct morphologies. This work explores an alternative approach through a mechanism that leads to a wide range of intricate and topologically non-trivial patterns. The mechanism is described by the self-dual Ginzburg-Landau theory and, possibly, other Maxwell-Higgs models. It gives rise to unique spatial flux and condensate spatial profiles observed in superconductors between the two conventional superconductivity types I and II.
RESUMO
Cluster formation is a focus of interdisciplinary research in both chemistry and physics. Here we discuss the exotic example of this phenomenon in the vortex matter of a thin superconductor. In superconducting films, the clustering takes place because of particular properties of the vortex interactions in the crossover or intertype regime between superconductivity types I and II. These interactions are controlled by the two parameters that are responsible for the crossover, Ginzburg-Landau parameter κ, which specifies the superconducting material of the film, and film thickness d, which controls effects due to stray magnetic fields outside the sample. We demonstrate that their competition gives rise to a complex spatial dependence of the interaction potential between vortices, favoring the formation of chainlike vortex clusters.
RESUMO
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.