Heat changes accompanying magnetization processes in ferrites

A brief survey is given of the method of measurement of the small thermal changes which accompany changes in magnetization, together with an outline of the procedure for the discussion of experimental data based on current theories of ferromagnetic processes. New measurements are described on a series of ferrites which include nickel¿zinc, manganese¿zinc, magnesium¿zinc and lithium¿chromium specimens. Evidence is presented that domain boundary movements occur in low fields; in high fields rotation of domain vectors are paramount. The manganese¿zinc ferrite shows a peak in the thermal changes in low fields, whereas with all the other specimens at room temperature a `dip¿ is observed. The magneto-thermal behaviour of lithium¿chromium ferrite is in accord with its unusual magnetic properties.