Evidence of magnetic dipolar interaction in micrometric powders of the Fe50Mn10Al40 system: Melted alloys

Alcázar, G. A. Pérez; Zamora, Ligia E.; Tabares, J. A.; Piamba, J. F.; González, J.M.; Grenèche, Jean‐Marc; Martı́nez, Antonio; Romero, J.J.; Marco, José F.

doi:10.1016/j.jmmm.2012.09.035

Cited by 10 publications

(4 citation statements)

References 62 publications

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“…Figure 5 shows the zero-field cooled (ZFC) and field cooled (FC) magnetization curves up to 350 K. The ZFC magnetization curve shows a monotonic increase in the entire temperature range and does not merge with the FC curve. These facts suggest that the blocking temperature above which our nanoparticles would behave as a superparamagnetic system is higher than 350 K. Additionally, the FC magnetization curve remains almost constant in the measured temperature range, indicating the presence of strong dipolar magnetic interactions [37].…”

Section: Resultsmentioning

confidence: 72%

Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles

et al. 2013

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FeCo-alloy graphite-coated nanoparticles with mean particle diameter under 8 nm have been synthesized following a CVD carbon-deficient method. The superior magnetic properties of FeCo-alloy nanoparticles makes them good candidates to be used as magnetic filler in magneto-polymer composites. Thanks to the protective effect of the graphite shell, FeCo nanoparticles are stable under oxygen atmosphere up to 200 ° C. The as-prepared nanoparticles presented a highly long range chemically ordered core being ferromagnetic at room temperature with a saturation magnetization at room temperature close to the bulk value. After annealing at 750 K the saturation magnetization and the coercive field increase. To investigate the processes involved in the thermal treatment, the temperature dependence of the magnetization and the particle composition, size and structure have been characterized before and after annealing. Besides powder x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), a detailed study by means of advanced transmission electron microscopy (TEM) techniques has been carried out. In particular, aberration corrected scanning transmission electron microscopy (STEM), has shown that nanoparticles became faceted after the thermal treatment, as a mechanism to reach the thermodynamic equilibrium within the metastable phase. This outstanding feature, not previously reported, leads to an increase of the shape anisotropy, which in turn might be the origin of the observed increase of the coercive field after annealing.

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Section: Resultsmentioning

confidence: 72%

Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles

et al. 2013

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“…In all these systems, the dipolar magnetic interaction plays an important role. This type of interaction was recently detected in microparticulated powders in the Fe-Mn-Al [22], Fe-Si [23] and Fe-Al [24] systems.…”

Section: Introductionmentioning

confidence: 65%

Magnetism in Granular Systems II

Salazar

Alcázar

2015

J Supercond Nov Magn

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Considering that the dipolar magnetic interaction plays an important role in the study of the magnetic properties of nano-and microparticulated systems, in this work, we use the theoretical expression of the blocking temperature derived in the model recently proposed by the current authors (Salazar and Pérez Alcázar, J. Supercond. Nov. Magn. 25, [2213][2214][2215] 2012), with the aim of obtaining an expression for the variation of the coercive field, H c , with temperature. In this calculation, we assume that the anisotropy constant of the system depends on the temperature. We also use the model to report the way in which the specific heat behaves as a function of temperature.

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“…Recently, it was shown that this type of interaction is also present in microparticulated systems such as alloys of FeSi [6], Fe-Al [7] and Fe-Mn-Al [8]. In this study, we present theoretical calculations of the thermodynamic properties of a nanoparticulated system using the model proposed by Mørup-Tronc.…”

Section: Introductionmentioning

confidence: 99%

“…We use the total energy to calculate the magnetization, heat capacity, magnetic susceptibility, and blocking temperature in nanoparticulated systems. The application of our theory to experimental data on nanoparticulated systems [3][4][5] and for the Fe-Al, Fe-Si, and Fe-Mn-Al microparticulated granular systems [6][7][8] will be presented elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Magnetism in Granular Systems

Salazar

Alcázar

2012

J Supercond Nov Magn

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Previous experimental studies have shown that the magnetic dipolar interaction plays an important role in several magnetic properties of nanoparticulated systems. More recently, this type of interaction was detected in microparticles of Fe-Mn-Al, Fe-Si and Fe-Al systems. In this work, we apply the Mørup-Tronc (Phys. Rev. Lett. 72:3278, 1994) model for nanoparticulated systems in order to calculate some thermodynamic properties of these systems. We first calculated the total energy of a magnetic particle as the sum of its anisotropy energy and its total dipolar magnetic interaction with the other particles. The calculation is performed in such a way that the interaction energy has the same form as the anisotropy energy. We use the total energy to calculate the magnetization, heat capacity, magnetic susceptibility, and blocking temperature in nanoparticulated systems. The application of our theory to experimental data on nanoparticulated systems and for the Fe-Al, Fe-Si and Fe-Mn-Al microparticulated granular systems will be presented elsewhere.

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Evidence of magnetic dipolar interaction in micrometric powders of the Fe50Mn10Al40 system: Melted alloys

Cited by 10 publications

References 62 publications

Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles

Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles

Magnetism in Granular Systems II

Magnetism in Granular Systems

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