Spin Spring Behavior in Exchange Coupled Soft and High-Coercivity Hard Ferromagnets

The magnetization reversal processes in an epitaxial Fe/[Sm.sub.2][Co.sub.7] structure were investigated using the magneto-optical indicator film technique. The dependence of the magnitude and the orientation of the structure average magnetization have been studied on both cycling and rotating the external magnetic field. Magnetization reversal of the soft ferromagnet was found to proceed by the formation of exchange springs due to spin winding in both the thickness and perpendicular directions as adjacent subdomains with opposite chirality are created. Experimental data is compared with a theoretical estimation of the rotational hysteresis loop for a spin system containing a one-dimensional (single chirality) exchange spring. Index Terms--Exchange spring, magnetization reversal, permanent magnet, SmCo, thin film.