Ising-like dynamics and frozen states in systems of ultrafine magnetic particles

Abstract

We use Monte-Carlo simulations to study aging phenomena and the occurence of spinglass phases in systems of single-domain ferromagnetic nanoparticles under the combined influence of dipolar interaction and anisotropy energy, for different combinations of positional and orientational disorder. We find that the magnetic moments oriente themselves preferably parallel to their anisotropy axes and changes of the total magnetization are solely achieved by 180 degree flips of the magnetic moments, as in Ising systems. Since the dipolar interaction favorizes the formation of antiparallel chain-like structures, antiparallel chain-like patterns are frozen in at low temperatures, leading to aging phenomena characteristic for spin-glasses. Contrary to the intuition, these aging effects are more pronounced in ordered than in disordered structures.

5 pages, 6 figures. to appear in Phys. Rev. B

References in corpus (1)

• Frozen metastable states in ordered systems of ultrafine magnetic particles

Cited by in corpus (4)

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• Superspin glass aging behavior in textured and nontextured frozen ferrofluid