Local random magnetocrystalline and macroscopic induced anisotropies in magnetic nanostructures

• Published in: Journal of non-crystalline solids Vol. 354; no. 47; pp. 5089 - 5092
• Main Authors: Suzuki, K., Ito, N., Garitaonandia, J.S., Cashion, J.D., Herzer, G.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.12.2008; Elsevier
• Subjects: Coercivity; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Directional order; Exact sciences and technology; Exchange interaction; Magnetic anisotropy; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetically ordered materials: other intrinsic properties; Permeability; Physics; Random anisotropy; Exchange interaction; Directional order; Coercivity; 75.50.Tt; Random anisotropy; 75.50.Lk; Permeability; 75.30.Gw; 75.75.+a; Induced anisotropy (magnetic); Iron; Nanostructures; BCC lattices; Magnetic anisotropy; Coercive force; Nanocrystal; Iron base alloys; Grain size; Annealing; Magnetic field effects; Soft magnetic materials; Silicon alloys; Rotating field; Static field; Exchange interactions
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2008.06.118

To clarify the influence of the coherent field-induced anisotropies ( K u) on the exchange softening effect in magnetic nanostructures, the soft magnetic properties of both bcc-Fe and D0 3-Fe(Si)-based nanocrystalline alloys annealed under static and rotating fields were surveyed. The random anisotropy model with K u predicts that the grain size ( D) dependence of the coercivity changes from D 6 to D 3 when the ratio of the random magnetocrystalline anisotropy and K u is approximately 1 to 2. The D 3 dependence is seen in the bcc-Fe-based alloys where K u is ∼100 J/m 3, while such a dependence is absent from the D0 3-Fe(Si)-based alloys simply because their K u is as small as ∼10 J/m 3 and the D 3 dependence is completely overshadowed by other extrinsic coercivity mechanisms. The soft magnetic properties of the bcc-Fe-based alloys are improved dramatically by rotating field annealing, implying that the exchange softening in the bcc-Fe-based alloys is promoted by suppressing the strong K u.