Effect of hard layer demagnetization on the magnetization reversal of epitaxial Fe/SmCo spring magnets

Epitaxial Fe/SmCo bilayers, a classical exchange spring magnet system, have been of great interest for potential applications in permanent magnet and thermally assisted magnetic recording. In the epitaxial Fe/SmCo samples the magnetization reversal of the Fe layer is distinguishable from the SmCo layer, in that there are two separate switching steps in the major hysteresis loop. The onset of the SmCo layer switching is also the onset of irreversible magnetization reversal for the bilayer, which has been shown by the recent first-order reversal curve (FORC). The second-order reversal curve (SORC) allows to distinguish between the Fe and the SmCo layer contributions to the magnetization switching despite the change in interlayer exchange coupling.