Exchange bias effects in Fe nanoparticles embedded in an antiferromagnetic Cr2O3 matrix

Jordi Sort (1, 2) , Véronique Langlais (2) , Stefania Doppiu (2) , Bernard Dieny (1) , Santiago Suriñach (2) , J. S. Muñoz (2) , M. D. Baró (2) , Christophe Laurent (3) , Josep Nogués (4)

1 SPINTEC - SPINtronique et TEchnologie des Composants
2 UAB - Universitat Autònoma de Barcelona = Autonomous University of Barcelona = Universidad Autónoma de Barcelona
3 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
4 ICREA - Institució Catalana de Recerca i Estudis Avançats = Catalan Institution for Research and Advanced Studies

Powders consisting of ferromagnetic (FM) Fe nanoparticles, of about 7 nm in size, embedded in an antiferromagnetic (AFM) Cr2O3 matrix have been obtained by high-temperature reduction under a hydrogen atmosphere of a mixed Cr-Fe oxide. This FM-AFM system exhibits exchange bias effects, i.e. a loop shift (HE) and coercivity enhancement (ΔHC), when field-cooled through the N'eel temperature, TN, of Cr2O3. The exchange bias properties were measured as a function of temperature. HE and ΔHC are found to vanish at about TN(Cr2O3), indicating a good quality AFM matrix. Hence, high-temperature reduction of mixed oxides is demonstrated to be a suitable technique to develop new types of FM-AFM exchange-biased nanoparticles, from which novel applications of this phenomenon may be developed.

Mots clés: Fe nanoparticles; Magnetic properties; Cr2O3

Domaines: Matériaux

Jordi Sort, Véronique Langlais, Stefania Doppiu, Bernard Dieny, Santiago Suriñach, et al.. Exchange bias effects in Fe nanoparticles embedded in an antiferromagnetic Cr2O3 matrix. Nanotechnology, 2004, vol. 15, pp. S211-S214. ⟨10.1088/0957-4484/15/4/017⟩. ⟨hal-00915670⟩