Effect of Magnetic Interactions on Magnetic Remanence in a Fine Particle System

Sauviz P. Alaei, E. Dan Dahlberg

Research output: Contribution to journalArticlepeer-review


The magnetic field-dependent remanent magnetization and demagnetization of magnetite nanoparticles dispersed in a frozen isoparaffin oil have been measured as a function of magnetite concentration. Frozen ferrofluid samples with magnetite volume fractions between 7.1% and 0.03% were demagnetized using either thermal or dc demagnetization and were kept frozen at 77 or 4 K during measurement to restrict mechanical rotation and translation of the particles. The magnetization and demagnetization remanences of the frozen ferrofluid were measured and plotted parametrically in the magnetic field magnitude to produce Henkel and Δ M plots for comparison with the Wohlfarth model. The Henkel and ΔM plots of the ferrofluid samples with higher concentrations of magnetite deviated from the predictions of the Wohlfarth non-interacting model, consistent with demagnetizing interactions in the system. The magnitude of this deviation decreased with decreasing magnetite concentration. A simple model is presented that quantitatively explains the deviations from the expected relations and can be used in other systems to characterize magnetic interactions.

Original languageEnglish (US)
Article number7300709
JournalIEEE Transactions on Magnetics
Issue number8
StatePublished - Aug 1 2022

Bibliographical note

Publisher Copyright:
© 1965-2012 IEEE.


  • Henkel plot
  • Wohlfarth model
  • magnetic nanoparticles
  • magnetic remanence


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