Angular dependence of magnetic reversal in two-phased nanolayers

The reversal process of hard/soft/hard multilayer systems as functions of easy axis β and thickness Ls of the soft layer has been investigated within a micromagnetic approach. The nucleation field could be obtained for β = 0 and β = π/2 which decreases as Ls increases. The coercivity, on the other hand, decrease smoothly with the soft layer thickness disregarding to the value of β. The coercivity becomes the largest when β = π/2, while the corresponding nucleation field becomes negative for larger Ls. Thus the change of the magnetization proceeds slower for β = π/2, giving rise to an oblique hysteresis loop. In addition, the critical thickness for the soft layer is rather small, where the dominant coercivity mechanism changes from nucleation to pinning, suggesting that pinning is the main coercivity mechanism in the material. When β is an angle between 0 and π/2, a fully saturated state can never be reached. Thus the pure nucleation becomes meaningless and pinning is the dominant coercivity mechanism.