The effect of interface anisotropy on demagnetization progress in perpendicularly oriented hard/soft exchange-coupled multilayers

The demagnetization progress of various hard/soft multilayers with perpendicular crystalline anisotropy has been studied by a micromagnetic model, incorporating the effect of the interface anisotropy, which is evident on the nucleation field when the soft layer thickness is small. Both microscopic and macroscopic hysteresis loops as well as angular distributions for the magnetizations in the thickness direction have been calculated, taking into account of realistic values of the interface anisotropy. The formula for the nucleation field has been derived analytically, where the nucleation field increases linearly with the interface anisotropy for a wide thickness region. While the nucleation field could change by more than 90% due to the influence of the interface anisotropy, the interface anisotropy has no effect on the pinning field or the coercivity, but it has some slight influence on the angular distributions. On the other hand, positive interface anisotropy enhances the remanence and the energy products, whereas negative interface anisotropy deteriorates both of them. Comparison with the experimental data justifies our calculation, indicating that negative interface anisotropy should be avoided in the experiment.