Motion of a Ferromagnetic Domain Wall inFe3O4

Experiments have been made on a sample of ${\mathrm{Fe}}_3$ ${\mathrm{O}}_4$ cut from a single crystal in such a way that its ferromagnetic domain pattern includes an individual domain wall whose motion can be studied. This sample has a permeability which is high (about 5000) at low frequencies and drops off rapidly above 1000 cycles. A hysteresis loop and data on wall velocity $\mathrm{vs}$ applied field were also taken. The data are discussed in terms of recent developments in the theory of the ferromagnetic domain wall. It appears that this theory explains our data satisfactorily, and that in using it to explain our data we determine some of the fundamental magnetic constants of ${\mathrm{Fe}}_3$ ${\mathrm{O}}_4$. We are also able to gain some insight into domain wall motion in ferrites generally in this way.