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The Magnetic Microstructure of Nanostructured Materials

  • Rudolf Schäfer
Chapter

Abstract

The magnetic microstructure and magnetization processes of nanostructured materials are reviewed in a phenomenological way, mainly based on domain observation by magneto-optical Kerr microscopy. This covers nanocrystalline soft magnetic ribbons and films as well as nanostructured hard magnetic materials. For comparison also the domain structure in coarse-grained material and amorphous ribbons are briefly touched to provide the frame for the nanostructured materials.

In nanocrystalline ribbons or films, the random magnetocrystalline anisotropy of the ultrafine grain structure is largely averaged out by exchange coupling. The soft magnetic properties are rather controlled by uniaxial, induced anisotropies that are uniform on a scale much larger than the exchange length. The interplay between these uniform and the random anisotropy results in a different degree of microscopic magnetization disorder which is reflected in the magnetization processes.

In high-anisotropy materials with exchange-coupled grains in the 10 nm regime (exchange-enhanced nanocrystalline permanent magnets), a highly irregular domain structure is found, consisting of immobile and high-coercive patch domains. If exchange coupling between the grains is interrupted, the so-called interaction domains are observed due to the predominance of magnetostatic interactions between the (single domain) grains.

Keywords

Easy Axis Magnetocrystalline Anisotropy Uniaxial Anisotropy Soft Magnetic Property Amorphous Ribbon 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

Many domain pictures in the chapter on nanocrystalline ribbons have been obtained by Sybille Flohrer (IFW Dresden, now at Vacuumschmelze, Hanau). For their interpretation Giselher Herzer (Vacuumschmelze) made decisive contributions. He also provided us with most of the NdCuFeBSi ribbons for domain imaging. Many thanks to both of them. Thanks also to Jeffrey McCord (IFW Dresden) for fruitful discussion on thin film magnetism and to Ludwig Schultz (IFW Dresden) for his continuous support and interest in domain research.

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Leibniz Institute for Solid State and Materials Research (IFW Dresden), Institute for Metallic MaterialsDresdenGermany

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