ISSN:
1434-6036
Schlagwort(e):
PACS. 61.12.Ex Neutron scattering techniques (including small-angle scattering) – 75.30.Gw Magnetic anisotropy – 75.50.Tt Fine-particle systems; nanocrystalline materials – 75.75+aMagnetic properties of nanostructures – 81.07.-b Nanoscale materials and structures: fabrication and characterization
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract: Based on a micromagnetics model, we develop a method through which quantitative information on the volume-averaged mean-square magnetostatic stray field 〈|H b d|2〉 v due to non-zero divergences of the magnetization M within the bulk of a ferromagnetic body can be obtained by analysis of magnetic-field-dependent small-angle neutron scattering data. In the limit of high applied magnetic field H a, when the direction of M deviates only sligthly from H a, we have estimated a lower bound for 〈|H b d|2〉 v as a function of the external field, and we have applied the method to bulk samples of nanocrystalline electrodeposited Ni and Co and coarse-grained polycrystalline cold-worked Ni. The root-mean-square magnetostatic stray field, which is inherent to a particular magnetic microstructure, shows a pronounced field dependence, with values ranging from about 5 to 50mT. Even at applied fields as large as 1.7T, the quantity μ〈|H b d|2〉1/2 v of nanocrystalline Co is still 24mT, which suggests that contributions to the total magnetostatic field originating from the bulk are significant in nanocrystalline ferromagnets; therefore, 〈|H b d|2〉 v cannot be ignored in the interpretation of e.g. measurements of magnetization or spin-wave resonance. A comparison of 〈|H b d|2〉 v with the volume-averaged mean-square anisotropy field reveals that both quantities are of comparable magnitude.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1140/epjb/e2002-00336-1
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