Exchange-coupled Sm-Co/Nd-Co nanomagnets: correlation between soft phase anisotropy and exchange field

The effect of the magnetic anisotropy of the Nd-Co soft phase on its exchange field (H-ex) is reported for epitaxial Sm-Co/Nd-Co bilayers. It is found that H-ex gradually increases with anisotropy K of the soft phase. The experimental values of H-ex as well as its variation with K are quantitatively interpreted using an analytical model based on the formation of a partial domain wall on the soft phase side of the interface. The results suggest that one can enhance H-ex, and hence, the volume fraction of the soft phase for effective exchange spring coupling between the hard and soft phases, by tailoring the anisotropy of the soft phase. (C) 2002 American Institute of Physics.