Magnetization reversal processes of isotropic permanent magnets with various inter-grain exchange interactions

Magnetic reversal in Sm2Fe17Ny permanent magnets

Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets

We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual m...

Coherent radiation by magnets with exchange interactions

A wide class of materials acquires magnetic properties due to particle interactions through exchange forces. These can be atoms and molecules composing the system itself, as in the case of numerous magnetic substances. Or these could be different defects, as in the case of graphene, graphite, carbon nanotubes, and related materials. The theory is suggested describing fast magnetization reversal...

Improving exchange-spring nanocomposite permanent magnets

We demonstrate a counterintuitive approach for improving exchange-spring magnets. Contrary to the general belief that the exchange–spring interface must be ideal and atomically coherent, we thermally process, by annealing or high-temperature deposition, epitaxial Sm–Co/Fe thin-film bilayers to induce interfacial mixing. Synchrotron x-ray scattering and electron microscopy elemental mapping conf...

First order reversal curve studies of permanent magnets

First order reversal curve (FORC) diagrams are a useful tool to analyze the magnetization processes in magnetic materials. FORC diagrams are computed from measured first order reversal curves on sintered Nd 2 Fe 14 B magnets. It is shown that the FORC diagram simplifies if the first order reversal curves a desheared using the macroscopic demagnetizing field given by the geometry of the sample. ...