An inelastic neutron scattering study of hematite nanoparticles

Mikkel Fougt Hansen, Stine Nyborg Klausen, K Lefmann, K.N Clausen, Franz Bødker, Steen Mørup, M Telling

Research output: Contribution to journalConference articleResearchpeer-review

Abstract

We have studied the magnetic dynamics in nanocrystalline hematite by inelastic neutron scattering at the high-resolution time-of-flight spectrometer IRIS at ISIS. Compared to previous inelastic neutron scattering experiments an improvement of the resolution function is achieved and more detailed information is obtained. We have performed measurements at several temperatures ranging from 5 to 325 K. The particles are canted antiferromagnetic (weakly ferromagnetic) at temperatures at least down to 5 K. We study both superparamagnetic relaxation and collective magnetic excitations of the whole particle moment at the antiferromagnetic Bragg reflection. We have studied different weightings of the particle size distribution. The data and their temperature dependence can with good agreement be interpreted on the basis of the Neel-Brown theory for superparamagnetic relaxation and a model for the collective magnetic excitations. \(C) 2003 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalJournal of Magnetism and Magnetic Materials
Volume266
Issue number1-2
Pages (from-to)68-78
ISSN0304-8853
DOIs
Publication statusPublished - Oct 2003
Event4th International Conference on Fine Particle Magnetism - Pittsburgh, PA, United States
Duration: 14 Aug 200216 Aug 2002
Conference number: 4

Conference

Conference4th International Conference on Fine Particle Magnetism
Number4
CountryUnited States
CityPittsburgh, PA
Period14/08/200216/08/2002

Keywords

  • magnetic fluctuations
  • neutron scattering
  • superparamagnetic relaxation
  • hematite

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