Magnetic interactions and magnetization reversal in anisotropic La-Nd-Fe-B/Ta/Co multilayers and disks

Abstract Understanding the magnetic interactions and magnetization reversal behaviors in composite magnets is helpful for exerting the optimum magnetic properties. In this work, we found that the squareness of the hysteresis loop is weakened by increasing the thickness of Ta space-layer in La-Nd-Fe-B/Ta/Co multilayers, but improved by designing the Co layer as periodic arrays of disks. Magnetization reversal behaviors were studied using first order reversal curves (FORC) and magnetic force microscopy (MFM). It has been found that the nucleation and propagation of new domains mainly lead to the irreversible magnetization process. By patterning the Co layer as periodic arrays of disks, the dipolar interaction is enhanced due to the shape-dependent anisotropy of Co disks, leading to better squareness. Our results benefit to understand the magnetic interactions and magnetization reversal behaviors in La-Nd-Fe-B/Co composite systems.