Empacotamento de fios magnéticos em cavidades com um substrato não coesivo

Abstract

The packing of particles with magnetic properties explores interactions among them to spontaneously form chains or ordered structures. This approach finds applications in self-responsive systems and the organization of complex biological structures. This study investigates the packing patterns of particles with magnetic properties in a two-dimensional circular cavity. Two linear chains formed by neodymium spheres, shaped like wires, were injected diametrically opposite into a Hele-Shaw cell containing a non-interacting substrate of plastic spheres. The analysis highlights the influence of the initial dipole configurations and substrate quantity on the geometric properties emerging from the packing patterns. The probability distributions of loop areas follow a log-normal function, revealing a region where the curves intersect, and vertices exhibit similar probabilities regardless of the substrate quantity. The relationship between the number of loops and the packing fraction reveals an effective area for loop formation. The ratio of areas to perimeters is consistent with models of metallic wire packing. During the packing of magnetic wires with plastic substrates, qualitative differences in arrangements were observed. Addressing them quantitatively, the probability distribution of the shortest paths between nodes and the radial distribution function were analyzed. These analyses indicate a transition in the probability distribution relative to distances between spheres, shifting from unimodal to bimodal, and identifying structural arrangements in square and triangular networks among the first neighbors. The application of the ”BFGS” optimization method in minimizing the system’s energy allowed the identification of dipole orientation configurations, revealing the predominance of antiferromagnetic domains in the ”Loop” regime and ferromagnetic domains in the ”Spiral” regime. The energy per sphere in the ”Loop” regime is below the relative energy for the formation of an infinite chain of magnetic spheres. The variation of relative energy, with reference to the first contact between the wires, behaves similarly to what was established by Philipse e Maas (2002) for the approximation of magnetostatic bacterial chains. This study contributes to a more comprehensive understanding of the properties and behavior of magnetic particles in confined systems.