Exchange coupling mechanism for magnetization reversal and thermal stability of Co nanoparticles embedded in a CoO matrix

Dominique Givord (1) , Vassil Skumryev (2, 3) , Josep Nogués (2, 3)

1 LLN - Laboratoire Louis Néel
2 ICREA - Institució Catalana de Recerca i Estudis Avançats = Catalan Institution for Research and Advanced Studies
3 Department de Fisica

A model providing a semi-quantitative account of the magnetic behavior of Co nanoparticles embedded in a CoO matrix is presented. The results confirm that exchange coupling at the interface between ferromagnetic (FM) and antiferromagnetic (AFM) nanostructures could provide an extra source of magnetic anisotropy, leading to thermal stability of the FM nanoparticles. It is shown that perpendicular coupling between the AFM and FM moments may result in large coercivities. The energy barrier, which works against reversal is due to the AFM susceptibility anisotropy. The experimentally observed exchange bias is tentatively ascribed to pre-existing intrinsic canting of the AFM moments at the interface.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Dominique Givord, Vassil Skumryev, Josep Nogués. Exchange coupling mechanism for magnetization reversal and thermal stability of Co nanoparticles embedded in a CoO matrix. Journal of Magnetism and Magnetic Materials, 2005, pp.111. ⟨hal-00102531⟩