Eur. Phys. J. B 41, 171-175 (2004)
https://doi.org/10.1140/epjb/e2004-00306-7

Surface effects in α-Fe₂O₃ nanoparticles

¹ Centro Atómico Bariloche, 8400 S.C. de Bariloche, RN, Argentina
² ISM-CNR, Area della Ricerca di Roma, C.P. 10, 00016 Monterotondo, Roma, Italy

Corresponding author: ^a zysler@cab.cnea.gov.ar

Received: 20 February 2004
Published online: 12 October 2004

Abstract

The magnetic properties of 5 nm -Fe₂O₃ nanoparticles have been investigated by magnetization measurements on a sample consisting of homogeneously dispersed, non-interacting, nanoparticles in a polymer matrix. The results indicate that the magnetic properties are mainly determined by surface effects, which manifest themselves in high coercive field, high irreversibility field and shifted hysteresis loop, after field cooling. These effects come from surface anisotropy and exchange anisotropy, due to the coupling between the disordered surface magnetic structure, with multiple spin configurations, and the core antiferromagnetically ordered structure.