Intergrain interactions in nanocrystalline isotropic PrFeB-based magnets

An analysis of recoil loops measured during the demagnetization process has been carried out to obtain information about the nature of intergrain interactions in nanocrystalline isotropic PrFeB-based magnets. These interactions can be studied by plotting the deviations from the ideal value for the remanence given by the well-known Wohlfarth's relation. Two kinds of interactions are mainly responsible for possible deviations: magnetostatic and exchange interactions. Here, a Pr9.0Nd3.0Dy1.0Fe72.0Co8.0B6.9Zr0.1 alloy has been used to prepare a series:of nanocomposites by intensive milling with various amounts of Fe. Coupling phenomena have been studied by analyzing the evolution of the deltaJ values when varying the 1) Fe-content; 2) annealing temperature, i.e., grain size; and 3) measurement temperature, i.e., variation of the exchange length.