Neutron study of magnetic excitations in 8-nm -Fe2O3 nanoparticles

Luise Theil Kuhn, Kim Lefmann, Christian Robert Haffenden Bahl, S. Nyborg Ancona, Per-Anker Lindgård, Cathrine Frandsen, Daniel Esmarch Madsen, Steen Mørup

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Abstract

By use of inelastic neutron scattering we have studied magnetic fluctuations in 8-nm particles of antiferromagnetic alpha-Fe2O3 (hematite) as a function of temperature and applied magnetic fields. The fluctuations are dominated by uniform excitations. Studies have been performed on both coated (noninteracting) and uncoated (interacting) particles. We have estimated the magnetic anisotropy energy and found that the data are in good agreement with the value obtained from Mossbauer spectroscopy. The energy epsilon(0) of the uniform excitations depends strongly on the uncompensated moment, which is caused by finite-size effects, and we have estimated the size of this moment from the experimental neutron data. The field dependence of epsilon(0) for the interacting nanoparticles differs strongly from that of the noninteracting nanoparticles, and this is a result of the influence of exchange interaction between the particles.
Original languageEnglish
JournalPhysical Review B Condensed Matter
Volume74
Issue number18
Pages (from-to)184406 (9 pages)
ISSN0163-1829
DOIs
Publication statusPublished - 2006

Bibliographical note

Copyright 2006 American Physical Society

Keywords

  • RELAXATION
  • HEMATITE NANOPARTICLES
  • MODEL
  • SCATTERING
  • SPIN
  • INTERACTING PARTICLES
  • MOSSBAUER-SPECTRA
  • DYNAMICS
  • SIZE DEPENDENCE
  • FERRITIN

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