Effect of interparticle interactions on the magnetization spectrum of a concentrated ferrocolloid
DOI:
https://doi.org/10.7242/1998-2097/2017.4.3Keywords:
ferrocolloid, magnetic nanoparticles, nonlinear response, interparticle interactions, dynamic susceptibilityAbstract
The paper is devoted to the study of the magnetization spectrum of a concentrated ferrocolloid placed in a strong alternating magnetic field of low frequency. The field amplitude dependences of susceptibilities of the first and third magnetization harmonics are measured experimentally (the harmonic susceptibility is defined here as the ratio of the harmonic amplitude to the field amplitude). It was found that these dependences are strongly determined by concentration of dispersed phase. The first harmonic susceptibility monotonically decreases with an increasing amplitude, and the faster the decrease occurs the higher the sample concentration is. The susceptibility of the third harmonic turns out to be a nonmonotonic function of the amplitude; the corresponding dependences have distinct maximum. With an increase in the particle concentration, the position of the susceptibility maximum of the third harmonic shifts toward smaller amplitudes. The experimental data obtained in this work can be well described in a wide range of concentrations and amplitudes by means of the so-called second-order modified mean-field model, which correctly takes into account the effect of interparticle interactions on magnetic properties of ferrocolloids.
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