Affiliation: | a Laboratoire de Magnétisme Louis Néel, CNRS, 166X, 38042, Grenoble cedex, France b Instituto de Física, Universidade de São Paulo, C.P. 20516, São Paulo, S.P., Brazil c Sumitomo Special Metals Co. Ltd., Mishimagun, Osaka 618, Japan |
Abstract: | We studied the coercivity in magnets of composition R17Fe83−χBχ (R = Nd, Pr and χ = 8, 30), using measurements of the coercive field Hc, its angular dependence, and the magnetic viscosity coefficient Sv, 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 Hc(T). |