Activation volumes of reversal in Tb-Fe-Co thin films

The minimum activation volumes for magnetooptic (MO) films of different thicknesses have been determined. If nucleation of a magnetic reversal is assumed to be cylindrical, then the minimum diameter than nucleates the reversal appears to be in inverse proportion to the film thickness. This may indicate that the maximum storage density achievable with these materials may be dependent on their thickness. Analysis of the field variation of the activation volume indicates that the thinner film may have a more uniform grain volume. It is noted that activation volumes are potentially useful as a method of determining the minimum domain size. In addition, the form of the fluctuation field can give information on the distribution of anisotropy and grain volumes