Domain wall pinning versus nucleation of reversed domains in R-Fe-B magnets (invited)

Abstract

The validity of nucleation and domain wall pinning models has been examined in R-Fe-B magnets by correlating the hard magnetic properties with the microstructure and magnetic domain structure. The nucleation model can be used to explain the magnetic properties of R-Fe-B magnets at low temperatures, but it fails at high temperatures. On the other hand, domain wall pinning can explain the magnetic properties over a much wider temperature range (up to the Curie temperature). The magnetic and structural data suggest that the coercivities (Hc) of powders and stoichiometric melt-spun ribbons are due to "strong pinning" by a random distribution of pins while the H c of sintered magnets and ribbons with off-stoichiometric composition are due to "localized pinning" at grain boundaries.