title: Revealing the signature of dipolar interactions in dynamic spectra of polydisperse magnetic nanoparticles.
abstract: We investigate, via a modified mean field approach, the dynamic magnetic response of a polydisperse dipolar suspension to a weak, linearly polarised, AC field. We introduce an additional term into the Fokker-Planck equation, which takes into account dipole-dipole interaction in the form of the first order perturbation, and allows for particle polydispersity. The analytical expressions, obtained for the real and imaginary dynamic susceptibilities, predict three measurable effects: the increase of the real part low-frequency plateaux; the enhanced growth of the imaginary part in the low-frequency range; and the shift of the imaginary part maximum. Our theoretical predictions find an experimental confirmation and explain the changes in the spectrum.
authors.affiliation: Ural Federal University, Lenin av. 51, 620000, Ekaterinburg, Russia.
authors.forename: Alexey O
authors.initials: AO
authors.lastname: Ivanov
authors.affiliation: Ural Federal University, Lenin av. 51, 620000, Ekaterinburg, Russia.
authors.forename: Vladimir S
authors.initials: VS
authors.lastname: Zverev
authors.affiliation: Ural Federal University, Lenin av. 51, 620000, Ekaterinburg, Russia and University of Vienna, Sensengasse 8, 1090, Vienna, Austria. sofia.kantorovich@univie.ac.at.
authors.forename: Sofia S
authors.initials: SS
authors.lastname: Kantorovich