Nanostructure of granular Co-SiO 2 thin films modified by thermal treatment and its relationship with Giant Hall Effect

SOCOLOVSKY, L. M.; OLIVEIRA, C. L. P.; DENARDIN, J. C.; KNOBEL, M.; TORRIANI, I.

Physical Review B - Condensed Matter and Materials Physics

American Physical Society

Año: 2005 vol. 72 p. 18442 - 18442

0163-1829

Granular cosputtered Co52͑SiO2͒48 thin films were thermally treated at different temperatures and theirmagnetotransport and structural properties were investigated. Hall resistivity increases with annealing tempera-ture ͑Ta͒, up to Ta = 250 ° C, and then decreases to a minimum for Ta = 400 ° C. The structural analysis wasbased on small-angle x-ray scattering results. A model of a polydisperse system of hard spheres was used toretrieve structural parameters. Results reveal that a volume fraction of Co atoms ͑approximately 25%͒ areforming nanospheres. The giant Hall effect depends on a particular combination of nanoparticle diameter, sizedistribution, and interparticle distance.