Coherent and Incoherent Magnetization Processes in Powders

The magnetic properties of a random assembly of uniaxial noninteracting particles are considered on the basis of two extreme mechanisms of irreversible magnetization changes: (a) coherent, and (b) completely incoherent reversals. The bulk properties are determined as weighted averages, the weighting factor ${\mathrm{f(H}}_0)$ corresponding to the variation of the critical field $H_0$ . Special integral expressions involving the bulk properties are independent of $f$ , and may thus be used to differentiate between the mechanisms (a) and (b). Methods are suggested for determining $f$ from the field dependence of the properties considered. An approximate criterion for neglecting particle interaction in this analysis is given.