Angular Variation of Coercive Force in Permanent Magnet Materials

Abstract

The following model is taken for a permanent magnet material: (1) A distribution of coercive forces is present, and (2) H_c is determined by a nonrotational process such as domain wall motion. This should be a good description of a powder material in which H_c is much less than 2K/M. From a given H_c distribution, one can then compute H_c as a function of peak magnetizing field for an aligned sample in various directions. One can also compute H_c 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.