Ferromagnetic and speromagnetic behavior in a rapidly quenched Bi2O3-CuO-Fe2O3 system

Abstract

Ternary oxides in the system Bi2O3-CuO-Fe2O3 were prepared by rapid quenching from the melt. In the x-ray amorphous region, ferromagnetic behavior was observed. The amorphous (Bi2O3)25(CuO)25(Fe2O3)50 specimen shows an irreversible thermomagnetization process below about 200 K, indicating the existence of magnetic frustration. Two kinds of 57 Fe Mössbauer absorption spectra indicate that at room temperature this specimen is composed of two magnetic phases: paramagnetic and ferromagnetic. Below about 200 K, the paramagnetic spins seem to gradually assume a speromagnetic order. On the other hand, the ferromagnetic phase may exist as less disordered clusters or microcrystals, and the cluster size is estimated to be about 100–300 Å. The magnetic frustration seems to be caused by the competition between exchange interactions at the interface of the ferromagnetic clusters and the speromagnetic matrix.