Influence of FeCo-interlayer thickness on remanence and coercivity in SmCo/FeCo/SmCo triple-layer films

The dependence of reduced remanence (Mr/Ms) and coercivity of Sm22Co78/Fe65 Co35/Sm22Co78 triple-layer films on Fe65Co35, soft-magnetic interlayer thic kness, d, was systematically investigated. All the hysteresis loops of the triple-layer films exhibit a single-phase behavior, reflecting a strong exc hange coupling between soft- and hard-magnetic phases. Mr/Ms shows a monoto nic increase with increasing the Fe65Co35 thickness, d, and the coercivity exists a peak with increasing d. From the plot of the interaction-based dev iation parameter Delta M (H) of two principle remanence curves (isothermal remanence magnetization and dc-demagnetization remanence) versus applied fi eld, a a negative interaction profile was observed, indicating a negligible inter-granular exchange coupling within hard-magnetic grains.