Thermal stability of Co-modified iron oxides. III. Effect on overwrite, erasability and dynamic coercivity

For pt.II see ibid., vol.MAG-23, p.48 (1987). The instability properties of Co-modified iron oxides are closely related to the volume scaling factor (i.e. the Co-containing/Co-free volume ratio). It is shown that this factor influences the audio erasability (in the video mode) and the ratio between printing and storage coercivity. Under such circumstances, bulk doped materials are found to be very unstable. However, the nature of the Co-containing phase can also have a large influence on the stability properties so that bulk-doped materials can be stabilized to some extent. Such improvement can be accounted for by the single ion contribution to the magnetocrystalline anisotropy constant and to its temperature dependence. The influence of the volume scaling factor on overwrite is also discussed