Controlled magnetic properties of Ni nanoparticles embedded in polyimide films
2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 76, no 17, 174432- p.Article in journal (Refereed) Published
We have studied the magnetic properties of Ni nanoparticles incorporated in polyimide films using dc- and ac-magnetization measurements. Transmission electron microscopy images reveal that both the mean particle diameter (dave) and the volume fraction of particles (ηave) in the composite layer can be controlled independently. In a series of samples with fixed dave, the system with the lowest ηave behaves magnetically as an ensemble of noninteracting superparamagnets. With increasing ηave, typical signatures of the dipole-dipole interparticle interaction, such as an enhanced blocking temperature, are observed. In dense systems, with a particle concentration above the threshold for geometrical percolation, the magnetic response is ferromagnetic due to the exchange interaction between particles in direct contact.
Place, publisher, year, edition, pages
2007. Vol. 76, no 17, 174432- p.
IdentifiersURN: urn:nbn:se:uu:diva-15096DOI: 10.1103/PhysRevB.76.174432OAI: oai:DiVA.org:uu-15096DiVA: diva2:42867