The influence of the magnetic properties of the amorphous matrix on the macroscopic behavior of soft nanocrystalline materials is analyzed. The random-anisotropy model is generalized to two magnetic phase systems. It is shown that recent observations dealing with a magnetic hardening at the first stage of nanocrystallization and a magnetic hardening at temperatures close to the matrix Curie temperature can be well understood with this generalization.

Exchange interactions between ferromagnetic layers through paramagnetic spacers have been widely observed and studied in thin multilayers. In this paper we report an experimental analysis of the exchange correlation length in soft ferromagnetic nanocrystals. It has been observed that for an average distance between crystallites below 5 nm they are coupled by exchange interactions even above the Curie temperature of the amorphous matrix. The experiment indicates that exchange can propagate through noncrystalline paramagnetic layers. An estimation of the exchange strength has been made.