Understanding the interaction of soft and hard magnetic components in NdFeB with first-order reversal curves
Sven Erik Ilse, Felix Groß, Gisela Schütz, Joachim Gräfe, E. Goering
Abstract
First-order reversal curve (FORC) measurements are a powerful tool to study magnetization reversal processes and interactions in heterogeneous systems with broad coercivity distributions. In NdFeB hard magnets an additional soft magnetic component is often observed possibly originating from damaged surface grains. Here we use FORC to study the reversal processes and interactions in these permanent magnets at different temperatures between 50 and 350 K. The measured reversal curves reveal a strongly coupled switching of the soft and hard magnetic components above 250 K. Below this temperature the two components are decoupled and switch almost independently. This decrease in effective interaction at lower temperatures is also observed in the FORC diagrams by a relative reduction in intensity of the so called interaction peak. This result proves that FORC is a powerful method, contributing to a better understanding of magnetization reversal processes and interactions in permanent magnets.