Relaxation phenomena in ensembles of CoFe sub(2O) sub(4) nanoparticles

Collective magnetic behavior of CoFe sub(2O) sub(4) nanoparticles with diameters of 76, 16, 15 and 8 nm, respectively, prepared by different chemical methods has been investigated. Particle composition, size and structure have been characterized by inductive coupled plasma (ICP), transmission electr...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2012-03, Vol.324 (6), p.1182-1188
Main Authors: Bittova, B, Vejpravova, JPoltierova, Morales, M P, Roca, A G, Mantlikova, A
Format: Article
Language:English
Subjects:
Diffraction
Inductively coupled plasma
Isotherms
Magnetic permeability
Magnetic properties
Magnetization
Nanoparticles
Transmission electron microscopy
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Summary:Collective magnetic behavior of CoFe sub(2O) sub(4) nanoparticles with diameters of 76, 16, 15 and 8 nm, respectively, prepared by different chemical methods has been investigated. Particle composition, size and structure have been characterized by inductive coupled plasma (ICP), transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). Basic magnetic properties have been determined from the temperature dependence of magnetization and magnetization isotherms measurements. The three samples exhibit characteristic of a superparamagnetic system with the presence of strong interparticle interactions. Magnetic relaxation phenomena have been examined via frequency-dependent ac susceptibility measurements and aging and memory effect experiments. For the particles coated with oleic acid, it has been demonstrated that the sample reveals all attributes of a super-spin glass (SSG) system with strong interparticle interactions.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2011.11.005