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Magnetization and Mossbauer study of partially oxidized iron cluster films deposited on HOPG

Nils Tarras-Wahlberg ; S. Kamali ; Mats Andersson (Institutionen för tillämpad mekanik, Förbränning ; Institutionen för fysik (GU)) ; C. Johansson ; Arne Rosen
Journal of Magnetism and Magnetic Materials (0304-8853). Vol. 367 (2014), p. 40-46.
[Artikel, refereegranskad vetenskaplig]

Iron clusters produced in a laser vaporization source were deposited to form cluster assembled thin films with different thicknesses on highly oriented pyrolytic graphite substrates. The development of oxidation of the clusters with time, up to three years, was investigated by magnetic measurements using an alternating gradient magnetometer. Furthermore, to receive information about the oxidation states, clusters of 57Fe were studied using Mossbauer spectroscopy. The magnetic analysis shows a time evolution of the saturation magnetization, remanence, and coercivity, determined from the hysteresis curves characteristic of a progressing oxidation. The different thicknesses of the iron cluster films as well as a protective layer of vanadium influence the magnetic properties when the samples are subjected to oxidation with Lime. While the saturation magnetization and remanence decrease and reach half the initial values for almost all the samples after three years, the coercivity increases for all samples and is more substantial for the thickest sample with a vanadium protective layer. This value is three folded after three years. Furthermore, based on a core-shell model and using the saturation magnetization values we have been able to quantitatively calculate the amount of the increase of Fe-oxide as a function of time. The Mossbauer spectroscopy shows peaks corresponding to iron metal and maghemite.

Nyckelord: Nanoparticle Iron cluster, Thin film, Iron oxide, Mossbauer spectroscopy, Magnetization

Denna post skapades 2014-08-28. Senast ändrad 2014-10-14.
CPL Pubid: 202075


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Institutionen för fysik (GU) (GU)
Institutionen för tillämpad mekanik, Förbränning (2007-2017)



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