Short-range antiferromagnetic correlations in spin-glass-like iron antimonate of composition FeSbO4

Abstract

The magnetic susceptibility data recorded from rutile-related iron antimonate of composition FeSbO4 in low applied magnetic fields show features such as susceptibility peaks and irreversibility which are characteristic of spin-glass-like behaviour. A small peak at approximately 70 K and a broad peak at approximately 25 K were observed in the zero-field-cooled (ZFC) magnetic susceptibility data. Neutron powder diffraction patterns recorded at temperatures between 160 and 80 K show that antiferromagnetic correlations develop within the (001) plane. The correlation length of the spins increases to a maximum of approximately 30 AA with decreasing temperature within this temperature range. A saturation of the antiferromagnetic correlation length is observed at temperatures below approximately 70 K. The results show that the magnetic behaviour of iron antimonate is considerably more complex than the canonic examples of random field Ising systems such as Mn1-xZnxF2 or canonic insulator spin-glasses such as Eu1-xSrxS. The authors suggest here that the peak in the ZFC magnetic susceptibility data at approximately 70 K may be associated with an inhibited antiferromagnetic transition which may be related to the thermally activated dynamics recently observed in different kinds of random magnetic systems. The broad peak at approximately 25 K may be associated with the dynamic crossover of the magnetic moments without a modification of the antiferromagnetic correlations.