Effect of surface magnetism on ferromagnetic films with an antidote lattice: Monte Carlo simulation

This article presents a Monte Carlo simulation of thin ferromagnetic films with an antidote lattice in an external magnetic field. The simulation studies films with an easy magnetization axis described by the Ising model. The Metropolis algorithm and finite-dimensional scaling theory are used to simulate the film behavior. The antidote lattice is an ordered array of square pores. The pores are located at the nodes of a regular square grid. The lattice period remains constant in the calculations, while the pore sizes vary. The calculations result in hysteresis loops for films with different thicknesses and pore sizes of the antidote lattice at different ratios of exchange constants. The calculations show that surface magnetism can have a different effect on the dependence of the coercive force on the pore size. At ratios of exchange constant close to unity, the antidote lattice reduces the coercive force and magnetization energy. At large relative values of the surface exchange constant, the antidote lattice increases the coercive force in the film. Calculations show the existence of conditions under which the antidote lattice does not affect the film magnetization. The article considers the case of large pore sizes. A sharp increase in coercive force is observed in this case. If the pore size exceeds 90 % of the antidote lattice period, then a sharp decrease in coercive force occurs. The simulation results are in good agreement with the experimental data.