Magnetic Properties of Nanoparticles of Antiferromagnetic Materials

Steen Mørup, Cathrine Frandsen, Franz Bødker, Stine Nyborg Klausen, K. Lefmann, P.A. Lindgard, Mikkel Fougt Hansen

Research output: Contribution to journalConference articleResearchpeer-review

Abstract

The magnetic properties of antiferromagnetic nanoparticles have been studied by Mossbauer spectroscopy and neutron scattering. Temperature series of Mossbauer spectra of non-interacting, superparamagnetic hematite nanoparticles were fitted by use of the Blume-Tjon relaxation model. It has been found that the magnetic anisotropy energy constant increases significantly with decreasing particle size. Neutron scattering experiments on similar samples give new information on both superparamagnetic relaxation and collective magnetic excitations. There is good agreement between the values of the parameters obtained from Mossbauer spectroscopy and neutron scattering. In samples of interacting hematite nanoparticles, the relaxation was significantly suppressed. The Mossbauer data for these samples are in accordance with a mean field model for an ordered state of strongly interacting particles. Mixing nanoparticles of hematite with CoO nanoparticles resulted in suppression of the superparamagnetic relaxation, whereas NiO nanoparticles had the opposite effect.
Original languageEnglish
JournalHyperfine interactions
Volume144
Issue number1
Pages (from-to)347-357
ISSN0304-3843
DOIs
Publication statusPublished - 2003
Event5th Seeheim Workshop on Mossbauer Spectroscopy - Seeheim, Germany
Duration: 21 May 200225 May 2002
Conference number: 5

Conference

Conference5th Seeheim Workshop on Mossbauer Spectroscopy
Number5
CountryGermany
CitySeeheim
Period21/05/200225/05/2002

Keywords

  • Mossbauer spectroscopy
  • magnetic nanoparticles
  • superparamagnetic relaxation
  • neutron scattering

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