Training effect of exchange bias in γ-Fe2O3 coated Fe nanoparticles

R. K. Zheng*, G. H. Wen, K. K. Fung, Xixiang Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

Training effect of exchange bias in the γ-Fe2O3 coated Fe nanoparticles were studied. The experimental results indicate that the frozen spins in γ-Fe2O3 shells are responsible for both the horizontal and vertical shifts of the field-cooling hysteresis loops. To understand exchange bias and training effect in the nanoparticles, we modified the Stoner-Wohlfarth model by adding the unidirectional anisotropy energy term to the total energy. It is found that the exchange bias and training effect in the nanoparticles can be well interpreted within the modified model. Since the configuration of the frozen spins was gradually varying as the applied field cycled for the hysteresis loop measurements, the number of the spins frozen along the cooling-field direction decreased, consequently, the exchange bias field HE became smaller.

Original languageEnglish (US)
Article number214431
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume69
Issue number21
DOIs
StatePublished - Jun 1 2004

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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