Ferromagnetic glass on the base of aggregates of Ni amorphous nanogranules

D. S. Ilyushenkov, V. I. Kozub, I. N. Yassievich, T. T. Nguyen, E. H. Bruck

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)


We have studied theoretically (including computer simulations) magnetic properties of aggregates of ferromagnetic amorphous nanogranules in the presence of direct exchange between the neighboring granules and random anisotropy fields. We show that such a system can be considered as ferromagnetic glass. We demonstrate (basing on analytical considerations as well as on the results of numerical simulations) that the system is decomposed to clusters or domains with nearly collinear orientation of magnetization. The size of the domains depends on the ratio of the exchange interaction and random anisotropy. For quasi-2D structures we predict that the dipoledipole interactions between the granules lead to a formation of magnetic vortices. Moreover, the computer simulations also reproduce the puzzling increase of the thermoremanent magnetization observed experimentally, which is expected to be a result of a temperature-dependent decrease in the anisotropy (or a temperature-dependent increase in the exchange). We also consider the structures with weak intergranular exchange and show that they are characterized by the presence of two critical temperatures.

Original languageEnglish
Pages (from-to)1588-1592
JournalJournal of Magnetism and Magnetic Materials
Issue number11
Publication statusPublished - 2011
Externally publishedYes


  • Amorphous monodisperse nanoparticles
  • Ferromagnetic glass
  • Magnetic properties of nanoparticles


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