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.

• Received 18 October 1993

DOI:https://doi.org/10.1103/PhysRevB.49.7064