Temperature dependence of superparamagnetic resonance of iron oxide nanoparticles
| Autor: | René Berger, Claude Estournès, Janis Kliava, Hervé Daubric, Jean-Claude Bissey |
|---|---|
| Přispěvatelé: | Centre de physique moléculaire optique et hertzienne (CPMOH), Université Sciences et Technologies - Bordeaux 1-Centre National de la Recherche Scientifique (CNRS), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC) |
| Jazyk: | angličtina |
| Rok vydání: | 2001 |
| Předmět: |
010302 applied physics
[PHYS]Physics [physics] Materials science Condensed matter physics Magnetic moment Magnetic domain Magnetism Thermal fluctuations 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials law.invention Magnetic anisotropy chemistry.chemical_compound chemistry law 0103 physical sciences [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] 0210 nano-technology Electron paramagnetic resonance Iron oxide nanoparticles ComputingMilieux_MISCELLANEOUS Superparamagnetism |
| Zdroj: | Journal of Magnetism and Magnetic Materials Journal of Magnetism and Magnetic Materials, Elsevier, 2001, 234 (3), pp.535-544. ⟨10.1016/s0304-8853(01)00347-x⟩ Journal of Magnetism and Magnetic Materials, Elsevier, 2001, 234 (3), pp.535-544 |
| ISSN: | 0304-8853 |
| DOI: | 10.1016/s0304-8853(01)00347-x⟩ |
| Popis: | Nanoparticles of maghemite (γ-Fe 2 O 3 ) are formed in a sol–gel silicate glass with a molar ratio Fe/Si of 2% by a treatment at 1000°C for 6 h. Electron paramagnetic resonance spectrum at 300 K shows a relatively narrow sharp line at g eff ≈2. As the temperature lowers to 5 K, the apparent resonance field decreases and the linewidth considerably increases. We develop a theoretical formalism based on a distribution of diameters or volumes of the nanoparticles following a lognormal. The nanoparticles are considered as single magnetic domains with random orientations of magnetic moments and thermal fluctuations of anisotropic axes. The individual line shape function is derived from the damped precession equation of Landau–Lifshitz. An appropriate linewidth expression is put forward, which account for the averaging of the fluctuations of orientations of the magnetic moments with respect to the magnetic field and to the magnetic anisotropy axes. A single set of parameters provides good fits to the spectra recorded at the different temperatures. The low-temperature blocking of the nanoparticle magnetic moments has been clearly evidenced in the resonance absorption intensity and the blocking temperature of the assembly of nanoparticles (averaged over the distribution in the nanoparticle volume) has been evaluated as 90 K. |
| Databáze: | OpenAIRE |
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