The ferromagnetic domain structure of haematite

Observations are reported of the ferromagnetic domain structure of natural and synthetic single crystals, made at temperatures close to the low temperature transition with the aid of an acetone based magnetic colloid. The domain structure of the synthetic crystals was found to change radically over a small temperature range centred around –12 °C. These changes are correlated with the measured remanent magnetization. Fairly extensive colloid patterns were found on the natural crystals at low temperatures but when the natural crystals were annealed at 1200 °C this low temperature colloid structure was no longer found.