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MA: Fachverband Magnetismus

MA 13: Magnetic Materials II

MA 13.4: Talk

Monday, March 14, 2011, 17:45–18:00, HSZ 401

Magnetization reversal of interaction domains in fine-grained textured Nd-Fe-B — •Juliane Thielsch, Ulrike Wolff, Volker Neu, Ludwig Schultz, and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, P.O. Box 27 01 16, D-01171 Dresden, Germany

Textured nanocomposite magnets attract a lot of interest due to their potential of exhibiting higher energy products than those of currently existing rare earth-transition metal permanent magnets. In such nanostructured materials interaction domains are expected in contrast to classical magnetic domain structures that are commonly known from e.g. sintered magnets. Domain structures of this kind occur due to the magnetic coupling between grains whose sizes are about equal or smaller than the expected single-domain grain size. For hot-deformed samples made of melt-spun Nd2Fe14B-type ribbons the existence of interaction domains due to magnetostatic coupling has been reported. We choose this system to investigate the magnetic microstructure in dependence of a magnetic field along the initial magnetization curve. Images taken with Magnetic Force Microscopy are correlated to global hysteresis measurements. We show for the first time how interaction domains evolve in a bulk magnetic system from the thermally demagnetized state to a field of 6T. The growing/shrinking of the interaction domains happens from the domain border to the inside. Hardly any reversal within one domain is visible which affirms the collective nature of those domains. At high magnetic fields domains are left that are in the range of the grain size which implies a grain by grain switching.