Exchange coupling field and blocking temperature of Mn-Ir/Ni-Fe top/bottombilayers with different stacking sequences and buffer layers

The exchange coupling field (H-ex) and the blocking temperature (T-b) were investigated with different stacking sequences and buffer layer materials. The top structure exhibited higher H-ex and T-b values than the bottom stru cture did. The samples which lad high H-ex values also exhibited high T-b v alues. The curve shape of the temperature dependence of H-ex/H-ex(initial) changed from a concave type to a convex type with an increase in H-ex and T -b values. The H-ex and the T-b values may be related to grain size and to the distribution of antiferromagnetic grain size at the interface of the an tiferromagnetic and the ferromagnetic layers. Ou the contrary, tile values of coercivity field (H-c) may be related to the interface morphology and to the grain size distribution.