Europhys. Lett.
Volume 72, Number 2, October 2005
Page(s) 249 - 255
Section Condensed matter: structural, mechanical and thermal properties
Published online 21 September 2005
Europhys. Lett., 72 (2), pp. 249-255 (2005)
DOI: 10.1209/epl/i2005-10224-x

Dipole-field-induced spin disorder in a nanocomposite soft magnet

A. Michels1, C. Vecchini2, O. Moze2, K. Suzuki3, J. M. Cadogan4, P. K. Pranzas5 and J. Weissmüller6, 7

1  Paul Scherrer Institute - Villigen PSI, Switzerland
2  CNR-INFM-S $\mth{^{\mathit 3}}$, Dipartimento di Fisica, Università di Modena e Reggio Emilia Modena, Italy
3  School of Physics and Materials Engineering, Monash University Melbourne, Australia
4  School of Physics, University of New South Wales - Sydney, Australia
5  GKSS Research Centre - Geesthacht, Germany
6  Forschungszentrum Karlsruhe, Institut für Nanotechnologie - Karlsruhe, Germany
7  Technische Physik, Universität des Saarlandes - Saarbrücken, Germany

received 19 April 2005; accepted in final form 17 August 2005
published online 21 September 2005

We report on a study of a magnetic nanocomposite of the Nanoperm type ( $\chem{Fe_{89}Zr_{7}B_{3}Cu_{1}}$) by magnetic small-angle neutron scattering (SANS). The understanding of the magnetic microstructure of these materials leaves much to be desired since we lack techniques capable of resolving the spin structure in the bulk with nanoscale resolution. Here, we present an analysis of the SANS signal by which one cannot only characterise the nanoscale structure of the spin system, but which allows to identify origin and structure of the perturbing field. In Nanoperm, an unusual angular anisotropy of the scattering suggests that the local spin misalignment decorates, as the most important perturbing field, dipole stray fields around the crystalline phase of the composite.

61.12.Ex - Neutron scattering (including small-angle scattering).
75.50.Tt - Fine-particle systems; nanocrystalline materials.
75.75.+a - Magnetic properties of nanostructures.

© EDP Sciences 2005