Modeling of interaction effects in granular systems

El‐Hilo, M.; Shatnawy, M; Rsheed, Anwar Al

doi:10.1016/s0304-8853(00)00443-1

Cited by 11 publications

(9 citation statements)

References 38 publications

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“…In general, H c increases or decreases depending on the type of cluster interaction. 39,40 For a positive dipolar type of interaction, the H c value is predicted to increase with increasing cluster concentration. 41 Therefore, in comparison with diluted samples, the measured H c value is higher.…”

Section: Resultsmentioning

confidence: 99%

Size Dependence of Inter- and Intracluster Interactions in Core–Shell Iron–Iron Oxide Nanoclusters

et al. 2012

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The room-temperature magnetic properties of core–shell iron–iron oxide nanoclusters (NCs) synthesized by a cluster deposition system were investigated, and their dependence on mean cluster size is discussed. In this study, the surface/boundary spins of clusters were not frozen and were thermally activated during the measurements. The intercluster interactions between clusters and intracluster interactions between the iron core (ferromagnetic) and iron oxide shell (ferrimagnetic) were investigated by field-dependent isothermal remanent magnetization and dc demagnetization measurements at room temperature. The Henkel and ΔM plots support the existence of dipolar intercluster interactions that become stronger with the growth of the clusters. The derivative of the initial magnetization curve implies that smaller clusters require lower fields and less time than larger ones to overcome various energy barriers before saturating the moments along the field direction. Coercive field and magnetization were also correlated with the interaction parameters. To compare the room-temperature magnetic results, one system was studied at low temperature, where exchange coupling at the interface between the oxide and metallic phases was observed through bias effect and anisotropy enhancement.

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Section: Resultsmentioning

confidence: 99%

Size Dependence of Inter- and Intracluster Interactions in Core–Shell Iron–Iron Oxide Nanoclusters

et al. 2012

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“…Accordingly the magnetisation of the system consists of two parts; one is due to clusters with low anisotropy energy barrier in comparison to thermal energy (superparamagnetic) and another is due to clusters with high anisotropy energy barrier (blocked). The magnetisation of such system is calculated using the well-established granular model [40]. The model is based on a modified Stoner-Wohlfarth theory taking into account thermal reversal of magnetisation vector over finite energy barrier.…”

Section: Magnetic Study: Results and Discussionmentioning

confidence: 99%

Room temperature ferromagnetism in nanocrystalline Ni-doped ZnO synthesized by co-precipitation

El‐Hilo

Dakhel

Ali-Mohamed

2009

Journal of Magnetism and Magnetic Materials

110

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“…The influence of particle-particle interactions was evidenced many years ago by experiments of Weili et al [3] and still is a challenge in its theoretical description [4,5]. Monte Carlo computer simulation reveals deeper insight in the connection of the local physical processes experienced by each particle and as a consequence the resulting behaviour of the whole system, as recently presented by Chantrell et al [6] who calculated the susceptibility of nanoparticle systems.…”

Section: Introductionmentioning

confidence: 93%

Magnetization measurements on frozen ferrofluids: an attempt to separate interaction and anisotropy influences

Michele

Hesse

Bremers

2006

J. Phys.: Condens. Matter

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In this contribution we focus on a novel way to perform and evaluate magnetization experiments on frozen ferrofluids or magnetic nanoparticles fixed in space. The basic idea is to project the behaviour of a real particle system onto a Stoner-Wohlfarth (SW) particle ensemble behaviour. Therefore first an ideal SW particle system acting as a reference system with unique particle sizes and orientation of easy axis was studied numerically by introducing a particle-particle interaction via a demagnetizing field. We have shown that for non-interacting SW particles a universal mean value rule holds that the magnetization measured after ZFC (zero field cooling) can be expressed as a mean value of the magnetization measured after PHFC and NHFC (positive and negative high field cooling) processes. Any deviation from this mean value rule is therefore due to non-SW behaviour (multidirectional anisotropy and interaction) only and can be derived from the magnetization measurements and be compared with simulations.By this new method it is possible to determine the mean value of the particle's anisotropy and the mean interaction which is expressed here as a magnetic field.We will report on experiments performed on frozen ferrofluids because these systems offer the possibility of complete thermal demagnetization after melting. In this contribution we describe experiments performed on two different frozen Co-based ferrofluids by SQUID magnetometry.

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Modeling of interaction effects in granular systems

Cited by 11 publications

References 38 publications

Size Dependence of Inter- and Intracluster Interactions in Core–Shell Iron–Iron Oxide Nanoclusters

Size Dependence of Inter- and Intracluster Interactions in Core–Shell Iron–Iron Oxide Nanoclusters

Room temperature ferromagnetism in nanocrystalline Ni-doped ZnO synthesized by co-precipitation

Magnetization measurements on frozen ferrofluids: an attempt to separate interaction and anisotropy influences

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