Dynamical properties of non-interacting Co nanoparticles

M. Respaud, M. Goiran, J. M. Broto, F. Lionti, L. Thomas, B. Barbara, T. Ould Ely, C. Amiens, B. Chaudret

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12 Citations (Scopus)


The dynamical properties of the magnetic moment of non-interacting cobalt nanoparticles dispersed in a polymer were investigated by ac-susceptibility (10 Hz < f < 104 Hz). We thus estimated the relaxation time of the magnetisation (τ) associated to the superparamagnetic properties of the particles, τ was found to follow the general Néel-Brown relaxation dynamics, with a pre-exponential relaxation time τ0 of 4(±2)·10-12 s for temperatures between 10 and 20 K. By combining the experimental results from ferromagnetic resonance, ac-susceptibility, and magnetisation, measurements giving the microscopic and macroscopic parameters, we demonstrate for the first time that the Coffey theoretical expressions were able to predict both τ and τ0 values. Finally, the thermal dependence of τ0 is discussed.

Original languageEnglish
Pages (from-to)122-127
Number of pages6
JournalEurophysics Letters
Issue number1
Publication statusPublished - Jul 1 1999

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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