The spin-canting anomaly in ferrimagnetic particles

The spin-canting anomaly, in which fine ferrimagnetic iron oxide particles are not completely saturated by very large applied magnetic fields, is investigated by high-field Mossbauer spectroscopy. Until now it has been thought that randomly oriented moments near surfaces were responsible. High-quality data are used to repudiate this view. Ferric ions on A sites are collinear with the applied field, whereas those on B sites are not quite collinear. Further, it is shown that the likely presence of antiferromagnetic impurities greatly confounds the interpretation of earlier experiments.