Comparison of the effects of regular and irregular physical structure on the magnetic microstructure of longitudinal thin films

Interaction effects in longitudinal thin films are investigated by computing delta I curves formed by comparison of the remanence curves using the Wohlfarth relation. Historically, throughout the literature, interpretation of magnetic microstructures has relied upon visual inspection of vector maps representing such configurations. However, in this paper, theoretical techniques are used to analyse the magnetic microstructures of simulated AC-erased and DC-demagnetised states; these take the form of a correlation function and Fourier analysis. The role of physical structure on such interactions is investigated by comparing the simulated curves generated from a system of grains lying on a radially isotropic structure with those of a system whose physical structure forms an hexagonal closed-packed (HCP) lattice. Different degrees of exchange coupling are considered. Disorder in the microstructure is shown to be responsible for a reduction in the magnitude of positive delta I values. It will be shown how the degree of cooperative switching during the magnetisation process is dependent on the underlying physical structure of the systems.