Significant deterioration of energy products in exchange-coupled composite magnets

Abstract

Hysteresis loops and energy products have been calculated reliably for a hard/soft/hard trilayer system with a deviation of easy axis β taken into account, which affects the coercivity significantly, and hence leads to much smaller energy products than those predicted by the previous theory. Such a deterioration is much sharper than the corresponding fall for a single-phased material and a 30° deviation of in-plane easy axis could result in a drop of the maximum energy product by more than 60. Consequently, the advantage of the composite phase can be realized only when the material is well oriented, which offers a possible explanation to the large discrepancy between the experimental and theoretical energy products. © 2012 American Institute of Physics.