Coercivity analysis in R17Fe83−χBχ magnets

Abstract We studied the coercivity in magnets of composition R 17 Fe 83−χ B χ (R = Nd, Pr and χ = 8, 30), using measurements of the coercive field H c , its angular dependence, and the magnetic viscosity coefficient S v , for temperatures between 4.2 and 500 K. The results are discussed in relation to a model which does not specifically consider the detailed mechanisms involved in magnetization reversal, but which provides information about the magnetic properties in the activation volume v where magnetization reversal is initiated. It is concluded that the ordering temperature in v tends to be slightly smaller than in the bulk and that the room temperature anisotropy in v is not strongly reduced with respect to the bulk value. Finally, a direct evaluation of the dipolar interactions is in good agreement with results obtained from H c ( T ).