Magnetic interactions in γ-Fe{sub 2}O{sub 3}@SiO{sub 2} nanocomposites

Journal Article · Thu Aug 07 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4891497· OSTI ID:22314553

El Mendili, Y.; Bardeau, J. -F.; Greneche, J. -M.; Grasset, F.; Cador, O.; Guizouarn, T. ^[1]

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1. Université de Rennes 1, Institut des Sciences Chimiques de Rennes, UMR UR1-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex (France)

Structural and magnetic properties of γ-Fe{sub 2}O{sub 3} nanoparticles of 4 nm diameter, dispersed into silica SiO{sub 2} matrix with a wide range value of volume fraction (0.05 to 1), were investigated. Produced γ-Fe{sub 2}O{sub 3}@SiO{sub 2} nanocomposites consist of an assembly of very small single domain magnetic object (<10 nm) with a random distribution of both inter-particle distance and direction of particle magnetic moment. We focused on the determination of a magnetic percolation threshold, defined as the magnetic particles concentration value above which the magnetic properties of isolated particles vanished in favor of a magnetic collective behavior induced by magnetic interactions. A percolation threshold value of 0.63 was obtained by a local probe technique such as {sup 57}Fe Mössbauer spectrometry and confirmed by global magnetic measurements through zero-field cooled, field-cooled, and ac susceptibility data. Below this threshold, dynamic ac magnetization measurements show a thermally activated Arrhenius dependence of the blocking temperature of superparamagnetic nanoparticles and above this critical value, one observes a slowing down of their dynamic properties, which lead toward the establishment of a spin-glass like state.

• OSTI ID: 22314553
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHANNELING
COMPOSITE MATERIALS
FERRITES
INTERACTIONS
IRON 57
IRON OXIDES
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MAGNETIZATION
NANOPARTICLES
NANOSTRUCTURES
SILICA
SILICON OXIDES
SLOWING-DOWN
SPECTROSCOPY
SPIN GLASS STATE
SUPERPARAMAGNETISM