Magnetization and Mossbauer study of partially oxidized iron cluster films deposited on HOPG
Journal article, 2014

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.

Nanoparticle Iron cluster

Magnetization

Thin film

Iron oxide

Mossbauer spectroscopy

Author

Nils Tarras-Wahlberg

University of Gothenburg

S. Kamali

University of California

Mats Andersson

University of Gothenburg

Chalmers, Applied Mechanics, Combustion

C. Johansson

RISE Acreo

Arne Rosen

University of Gothenburg

Journal of Magnetism and Magnetic Materials

0304-8853 (ISSN)

Vol. 367 40-46

Subject Categories

Condensed Matter Physics

DOI

10.1016/j.jmmm.2014.04.077

More information

Latest update

9/10/2018