Angular Variation of Coercive Force in Permanent Magnet Materials

The following model is taken for a permanent magnet material: (1) A distribution of coercive forces is present, and (2) Hc is determined by a nonrotational process such as domain wall motion. This should be a good description of a powder material in which Hc is much less than 2K/M. From a given Hc distribution, one can then compute Hc as a function of peak magnetizing field for an aligned sample in various directions. One can also compute Hc as a function of angle at constant peak magnetizing field. This may show a maximum at 0° even in quite large fields. Thus, such a maximum need not indicate the onset of Stoner‐Wohlfarth behavior. The computed curves may also show maxima in intermediate directions. The computed results are compared with experimental results on MnBi and Co5Y.