Ferromagnetic Resonance of Single-Domain Particles

Valstyn, E.; Hanton, J. P.; Morrish, A. H.

doi:10.1103/physrev.128.2078

Cited by 86 publications

(48 citation statements)

References 22 publications

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“…For K, or better for the absolute value of the anisotropy constant, we obtained the range K ≈ 2.4 × 10 4 -3.6 × 10 5 J/m 3 . These estimates of K compare surprisingly well with the magnitude of the first constant of magnetocrystalline anisotropy of bulk cubic maghemite which is equal to −2.5 × 10 4 J/m 3 [9]. This points to the conclusion that the energy barrier determining the time of relaxation of our magnetic particles to equilibrium is, beside their volumes, mostly governed by the magnetocrystalline anisotropy.…”

Section: Estimate Of the Energy Barriersupporting

confidence: 71%

Superparamagnetic properties of γ-Fe2O3 particles: Mössbauer spectroscopy and d.c. magnetic measurements

et al. 2006

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Particles of Fe oxide were prepared by chemical coprecipitation and their sizes were shown by TEM and confirmed by XRD to be in the range of 5 nm. The Mössbauer spectra at 120 K clearly indicated the absence of magnetite and presence of the maghemite (γ-Fe2O3) phase. We studied the transition of the system to superparamagnetic behaviour, which strongly depends on the relevant time window amounting to ∼ 10 −7 s for Mössbauer spectroscopy of 57 Fe and units of seconds for d.c. magnetic measurements. From the temperature dependences of magnetic moments of zero-field-cooled (ZFC)) and field-cooled (FC) samples, the distributions of blocking temperatures were determined. The comparison of the transition temperatures derived from these two types of measurements gave an independent estimate for the pre-exponential factor and the energy barrier and thus magnetocrystalline anisotropy in an order-of-magnitude agreement with the published data for bulk γ-Fe2O3.PACS : 61.46.Df, 75.30.Gw

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Section: Estimate Of the Energy Barriersupporting

confidence: 71%

Superparamagnetic properties of γ-Fe2O3 particles: Mössbauer spectroscopy and d.c. magnetic measurements

et al. 2006

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“…For cubic c-Fe 2 O 3 with negative anisotropy constant K, the numerical calculations of Valstyn et al predict four different resonance lines for nearly spherical samples and two lines for ellipsoidal samples with a/b > 1.30 [25]. For bulk samples only a single line has always been observed.…”

Section: Resultsmentioning

confidence: 99%

FMR and DSC study of maghemite nanoparticles in PMMA polymer matrix

Typek

Guskos

Szymczyk

et al. 2008

Journal of Non-Crystalline Solids

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“…According to Valstyn et al [14], and more recently Dutta et al [29], in the case of elongated ferro-or ferri magnetic nanoparticles, a double line is expected in the FMR spectrum. As temperature decreases, the line appearing at lower field would separate from the one at high field, which would remain at a constant resonance field.…”

Section: Interpretation Of Fmr Spectramentioning

confidence: 91%

“…Since the shape-dependent equation for single crystals derived by Kittel [12,13], subsequent attempts of explaining the FMR spectra from a theoretical point of view, treating single domain particles and including only the size and shape distribution of particles revealed a visible disagreement when an external magnetic field was applied during experiments [14]. Precisely, further models [15][16][17] which have taken into account the size distribution, dipolar and exchange interactions and thermofluctuational perturbations in the superparamagnetic regime, have resulted in better approaches to the intrinsic lineshape and resonance fields.…”

Section: Introductionmentioning

confidence: 99%