Saturation and Magnetization of Hexagonal Iron Oxide Compounds

The value of the saturation magnetization at absolute zero of BaO·6${\mathrm{Fe}}_2$${\mathrm{O}}_3$ and related compounds can be explained as due to noncompensated antiferromagnetism.

The Bloch wall formation in small particles is discussed. One is led to the assumption that in these materials Bloch walls are nucleated at imperfections. In specimens containing randomly oriented large crystals, Bloch wall formation becomes appreciable at a positive field strength of the order of $4\pi I_s$.

By orienting the crystals in a magnetic field ${\mathrm{}\left(\mathrm{BH}\right)\mathrm{}}_{max}$-values of 3×${10}^6$ gauss oersted have been obtained.

The critical diameter for wall formation changes with temperature. An excess of walls formed at a different temperature from the temperature of measurement may persist in a metastable equilibrium.