Magnetic field-dependent X-ray holography for magnetic imaging of interaction domains in nanostructured Nd-Fe-B permanent magnet

Nd-Fe-B magnets are essential for environmentally friendly energy conversion in electric motors and generators. Nanostructured magnets offer great potential for permanent magnets with a lower amount of critical heavy rare earths. Using X-ray holography, we aim to measure the magnetic domain structure of nanostructured hot-deformed Nd-Fe-B magnets at different external magnetic fields along the second quadrant of the hysteresis curve to understand the influence of microstructure on the formation of interaction domains and to unravel their complicated mechanisms of coercivity and magnetization reversal. The BOREAS beamline and MARES end station have proven to provide the necessary high-resolution magnetic imaging for studying the topology of the domains and the morphology of the domain walls with a resolution down to ~ 30 nm. We plan to use a combination of coherent diffractive imaging based on X-ray holography and heterodyne amplification of the weak magnetic scattering signal using a custom-built gold mask placed on top of the sample. With this technique, resolutions in the sub-10 nm range have recently been achieved.