Magnetic susceptibility curves of a nanoparticle assembly, I: Theoretical model and analytical expressions for a single magnetic anisotropy energy

Tournus, Florent; Bonet, Edgar

doi:10.1016/j.jmmm.2010.11.056

Cited by 37 publications

(27 citation statements)

References 32 publications

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“…1 are based on calculations which are in fact not comparable to what we did, even if they look similar (in particular, we insist on the fact that the author makes a bad usage of the ZFC analytical formula that we have derived, because he considers a constant t m ). Finally, a careful examination of our previous articles [2][3][4][5] will give a clearer view on the points discussed in this comment. V ¼ Ð 1 0 VqðDÞdD; and in the same way, the mean value X of any quantity X related to the particle size can be expressed as X ¼ Ð 1 0 XqðDÞdD.…”

Section: Discussionmentioning

confidence: 93%

“…In Ref. 2, it was clearly explained that a measurement at a constant temperature sweeping rate r T corresponds to an "effective waiting time" d t , or t m with the notation of Ref. 1, which varies with the temperature and the magnetic anisotropy energy (MAE) K ¼ K eff V (i.e., with the particle volume V).…”

Section: Progressive Crossover Modelmentioning

confidence: 99%

“…1 "Another confusing result in Ref. 12 is the effect of f 0 on the vðTÞ variation, which was considered not to be an important issue," whereas the influence of f 0 had been examined in our articles 2,3 (the f 0 dependence is explicitly given in the expression of T B and T X for instance) and we had written "many couples of f 0 and FIG. 1.…”

Section: "Blocking" Temperature Distributionmentioning

confidence: 99%

“…It is explained that the "volume and number weighted distribution are equally valid for the representation of distribution functions in nanoparticle magnetic systems" and the usual modelling approach (abrupt transition from a blocked to a superparamagnetic regime, at a given temperature) is compared to the more elaborate one (the "progressive crossover model (PCM)") introduced in our previous articles. [2][3][4] The importance of the f 0 value is also stressed. In this article, several statements are made in opposition to some of our previously published results.…”

mentioning

confidence: 99%

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Comment on “Nano-particle magnetism with a dispersion of particle sizes” [J. Appl. Phys. 112, 103915 (2012)]

Tournus¹,

Tamion²

2013

Journal of Applied Physics

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A recent paper1 examines zero field-cooled/field-cooled (ZFC/FC) susceptibility curves for nanoparticle assemblies with a size distribution. It is explained that the “volume and number weighted distribution are equally valid for the representation of distribution functions in nanoparticle magnetic systems” and the usual modelling approach (abrupt transition from a blocked to a superparamagnetic regime, at a given temperature) is compared to the more elaborate one (the “progressive crossover model (PCM)”) introduced in our previous articles.2–4 The importance of the f0 value is also stressed. In this article, several statements are made in opposition to some of our previously published results. Because we like to believe that these words were driven by a simple “misunderstanding” of our models and analysis, we would like to clarify some points in the present comment.

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Section: Discussionmentioning

confidence: 93%

Section: Progressive Crossover Modelmentioning

confidence: 99%

Section: "Blocking" Temperature Distributionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Comment on “Nano-particle magnetism with a dispersion of particle sizes” [J. Appl. Phys. 112, 103915 (2012)]

Tournus¹,

Tamion²

2013

Journal of Applied Physics

Self Cite

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“…A quantitative estimate of parameters μ and σ 2 , mean and variance of the distribution, respectively, can be obtained by fitting the ZFC magnetization curve at low field (H = 50 Oe) using the following formula: 37,38 ∫ ∫…”

Section: ■ Xrpd Measurementsmentioning

confidence: 99%

Spin Dynamics in Hybrid Iron Oxide–Gold Nanostructures

et al. 2015

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We report a broadband 1 H NMR study of the spin dynamics of coated maghemite and gold−maghemite hybrid nanostructures with two different geometries, namely dimers and core−shells. All the samples have a superparamagnetic behavior, displaying a blocking temperature (T B ∼ 80 K (maghemite), ∼105 K (dimer), ∼150 K (core−shell)), and the magnetization reversal time follows the Vogel−Fulcher law. We observed three different anomalies in 1 H NMR T 1 −1 versus T that decrease in amplitude when increasing the applied magnetic field. We suggest that the anomalies are related to three distinct system dynamics: molecular rotations of the organic groups (240 < T < 270 K), superparamagnetic spin blockage (100 < T < 150 K), and surface−core spin dynamics (T < 25 K). By fitting the T 1 −1 data with a heuristic model, we achieved a good agreement with magnetic relaxation data and literature values for methyl group rotation frequencies.

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Magnetically Assembled SERS Substrates Composed of Iron–Silver Nanoparticles Obtained by Laser Ablation in Liquid

et al. 2016

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The widespread application of surface-enhanced Raman scattering (SERS) would benefit from simple and scalable self-assembly procedures for the realization of plasmonic arrays with a high density of electromagnetic hot-spots. To this aim, the exploitation of iron-doped silver nanoparticles (NPs) synthesized by laser ablation of a bulk bimetallic iron-silver target immersed in ethanol is described. The use of laser ablation in liquid is key to achieving bimetallic NPs in one step with a clean surface available for functionalization with the desired thiolated molecules. These iron-silver NPs show SERS performances, a ready response to external magnetic fields and complete flexibility in surface coating. All these characteristics were used for the magnetic assembly of plasmonic arrays which served as SERS substrates for the identification of molecules of analytical interest. The magnetic assembly of NPs allowed a 28-fold increase in the SERS signal of analytes compared to not-assembled NPs. The versatility of substrate preparation and the SERS performances were investigated as a function of NPs surface coating among different thiolated ligands. These results show a simple procedure to obtain magnetically assembled regenerable plasmonic arrays for repeated SERS investigation of different samples, and it can be of inspiration for the realization of other self-assembled and reconfigurable magnetic-plasmonic devices.

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Magnetic susceptibility curves of a nanoparticle assembly, I: Theoretical model and analytical expressions for a single magnetic anisotropy energy

Cited by 37 publications

References 32 publications

Comment on “Nano-particle magnetism with a dispersion of particle sizes” [J. Appl. Phys. 112, 103915 (2012)]

Comment on “Nano-particle magnetism with a dispersion of particle sizes” [J. Appl. Phys. 112, 103915 (2012)]

Spin Dynamics in Hybrid Iron Oxide–Gold Nanostructures

Magnetically Assembled SERS Substrates Composed of Iron–Silver Nanoparticles Obtained by Laser Ablation in Liquid

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