EFFECT OF THE DIRECTION OF AN EXTERNAL APPLIED MAGNETIC FIELD ON THE MICROMAGNETIC PROPERTIES OF Fe CUBOIDS

Abstract

We present the results of the study of the micromagnetic properties and the magnetization dynamics of a system of Fe cuboids with a square base of length L = 120 nm and thickness, t = 9 nm, under free boundary conditions as a function of the angle of an in-plane applied external magnetic field, for which we have used the Ubermag micromagnetic program that uses the OOMMF package and the finite difference method with a cell size, c = 3 nm. Hysteresis loops show that the coercive field (Hc) decreases with increasing azimuthal angle, from one easy-magnetizing axis to the other; in turn, the remanent magnetization (Mr) remains constant and magnetization diagrams indicate the presence of magnetic domains and walls in the (x, y) plane, accompanied by a magnetization component that points, both, outward and inward of the plane. This behavior is associated with the type of anisotropy and the aspect ratio of the cuboid. Finally, energy graphs show how the competition between the dipole (Ed), the exchange (Eex), anisotropy (EK), and Zeeman (EZ) energies occurs along the hysteresis loops.