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Magnetic Interactions between Nanoparticles of Different Materials

  • Christopher W. Ostenfeld
  • Steen Mørup

Abstract

Samples consisting of nanoparticles of α-Fe2O3 and mixtures of α-Fe2O3 and NiO or CoO have been studied by Mössbauer spectroscopy in the temperature range 20–320 K. Nanoparticles of α-Fe2O3, which normally do not have a Morin transition above 5 K, exhibited a Morin transition when mixed with NiO nanoparticles. Pure hematite particles, coated with oleic acid, showed a typical superparamagnetic behaviour at higher temperatures, whereas a sample of uncoated particles was less affected by relaxation, indicating a strong influence of inter-particle interactions. Admixture of NiO nanoparticles resulted in a smaller influence of inter-particle interactions on the spectra of uncoated particles. Admixture of CoO nanoparticles did not induce a Morin transition in α-Fe2O3 particles, but unlike NiO particles, CoO nanoparticles significantly slowed down the superparamagnetic relaxation.

Keywords

Magnetic Anisotropy Mossbauer Spectrum Hematite Particle Quadrupole Shift Morin Transition 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2002

Authors and Affiliations

  • Christopher W. Ostenfeld
    • 1
  • Steen Mørup
    • 1
  1. 1.Department of PhysicsTechnical University of DenmarkKgs. LyngbyDenmark

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