Magnetization reversal models and the temperature dependence of the coercive force in melt spun PrNdFeB magnets

In this work we have studied the temperature dependence of several hysteresis parameters measured in PrNdFeB samples that were obtained from melt spun amorphous precursors crystallized by employing different heating rates. Analysis of the spin reorientation temperature by means of thermal evolution of the remanence and of the demagnetization differential susceptibility revealed the presence in all samples of at least two hard 2:14:1 phases (Nd rich and Pr rich, respectively). The demagnetization curves of most samples exhibited a single magnetization reversal process thus indicating that the hard phases were coupled. Despite the multiphase character of the samples, it was possible to carry out the analysis of the temperature dependence reversal process through micromagnetic and global models, and by accepting a linear variation of the intrinsic properties with the degree of substitution of Nd by Pr. Best fits for both models were obtained when using parameters corresponding to Nd-rich 2:14:1 phases, which indicates that the collective single reversal process is driven by the Nd-rich 2:14:1 grains. (C) 1997 American Institute of Physics.