Determination of anisotropy constants of ferromagnetic multilayers via fitting of Stoner-Wohlfarth Model

Historically the primary method of determining the anisotropy constants of a material has been the angle dependence of the Ferromagnetic Resonance (FMR), which makes use of the Larmor frequency of a spin precessing around an applied magnetic field. Anisotropy constants can also be determined by fitting the hysteresis curves to those predicted by the Stoner-Wohlfarth Model via a least-squares fitting algorithm. In this work the anisotropy energy was considered for both the bulk and the interface of ferromagnetic films. Preliminary results find the interface anisotropy constant of alloys of Fe, Co, and Mn to be larger than the bulk anisotropy, both of which are on the order of nanoJoules. This methodology also allows for the determination of the coupling constant between the layers of a multilayered system. This is the main advantage of this method over FMR. It should also be noted that magnetic hysteresis data is much more readily available than FMR data due to its specialized nature, opening up the possibilities of determining the anisotropy and coupling constants for a larger variety of samples.