Enhanced magnetic performance of aligned wires assembled from nanoparticles: from nanoscale to macroscale

Li, Qing X.; Kartikowati, Christina Wahyu; Iwaki, Toru; Okuyama, Kikuo; Ogi, Takashi

doi:10.1098/rsos.191656

Cited by 5 publications

(6 citation statements)

References 61 publications

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“…In such a case, the nature of the dipolar interaction changes from ferromagnetic to antiferromagnetic as the orientation of the anisotropy axis varied from perfectly collinear to perpendicularly aligned[45]. Our results with α = 0 • and 90 • are in perfect agreement with the work of Li et al and Yoshida et al[34,49]. We could not compare for other α as they have shown results only with two extremum α values.…”

supporting

confidence: 87%

“…Therefore, these ordered nanoparticles ensembles provide a rich theoretical framework to study the role of dipolar interaction and magnetic anisotropy on magnetic response. Much research efforts ranging from experimental to theoretical modelling have been devoted to unearthing the magnetic properties in such versatile systems [33][34][35][36][37][38][39]. Deng et al presented a detailed and very informative overview regarding forming an anisotropic assembly of MNPs [33].…”

Section: Introductionmentioning

confidence: 99%

“…The dipolar interaction is one of the main reasons for such a self-assembled system. Li et al analyzed the magnetic properties in dense arrays of magnetic nanoparticles using experiments [34]. They are found to possess enhanced magnetic properties along the array direction compared with the dispersed particles.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic Effect of Dipolar Interaction in Ordered Ensembles of Nanoparticles

Anand

2021

Preprint

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We implement extensive computer simulations to investigate the hysteresis characteristics in the ordered arrays (l x × l y ) of magnetic nanoparticles as a function of aspect ratio A r = l y /l x , dipolar interaction strength h d , and external magnetic field directions. We have considered the aligned anisotropy case, α is the orientational angle. It provides an elegant en route to unearth the explicit role of anisotropy and dipolar interaction on the hysteresis response in such a versatile system. The superparamagnetic character is dominant with weak dipolar interaction (h d ≤ 0.2), resulting in the minimal hysteresis loop area. Remarkably, the double-loop hysteresis emerges even with moderate interaction strength (h d ≈ 0.4), reminiscent of antiferromagnetic coupling. These features are strongly dependent on α and A r . Interestingly, the hysteresis loop area increases with h d , provided A r is enormous, and the external magnetic field is along the y-direction. The coercive field µ o H c , remanent magnetization M r , and the heat dissipation E H also depend strongly on these parameters. Irrespective of the external field direction and weak dipolar interaction (h d ≤ 0.4), there is an increase in µ o H c with h d for a fixed α and A r ≤ 4.0. The dipolar interaction also elevates M r as long as A r is huge and the field is along the y-direction. E H is minimal for negligible and weak dipolar interaction, irrespective of A r , α, and the field directions. Notably, the magnetic interaction enhances E H if A r is enormous and the magnetic field is along the long axis of the system. These results are beneficial in various applications of interest such as digital data storage, spintronics, etc.

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supporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Anisotropic Effect of Dipolar Interaction in Ordered Ensembles of Nanoparticles

Anand

2021

Preprint

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“…These materials are very interesting for their application as soft materials [2,3]. Such constructions using densely packed particles has also been explored with magnetic nanoparticles [4][5][6]. Another interesting example was reported by Merk, et al [7], where they found that using wood as a template, an anisotropic composite material is obtained, related to the hierarchical structure of wood.…”

Section: Introductionmentioning

confidence: 99%

Magnetostatic model for magnetic particle agregagates with cylindrical shapes

Carrera-Escobedo,

Hintze-Madonado,

Encinas-Oropesa

2023

Rev. Mex. Fís.

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Building micro and macro sized structures using compacted magnetic nanoparticles is a widely used approach that has proven a great potential as the basis for novel materials made by design. These materials are made by compactation of soft magnetic particles in the nano o micrometer sizes and their macroscopic properties are mostly governed by magnetostatic effects and the combination of the intervening shapes, namely those of the individual particles and that of the piece made with these particles. Herein a simplified mean-field model is presented to describe the magnetostatic effects in soft magnetic composites with cylindrical macroscopic shape made of densely packed ideal spherical soft magnetic particles. The model allows calculating the main magnetic parameters of the system as well as their most relevant tendencies as a function of its main parameters. Furthermore, the model has also been successfully applied to arrays of interacting macroscopic shapes, which provides a further controllable magnetic parameter.

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“…The coercivity is found to significantly modified by the direction of anisotropy axes. Using experiments, Li et al studied the hysteresis response in dense arrays of magnetic nanowires [44]. The coercive field and remanent magnetization are more significant with perfectly aligned anisotropy as compared to perpendicular orientation.…”

Section: Introductionmentioning

confidence: 99%

Relaxation in Ordered Assembly of Magnetic Nanoparticles

Anand

2021

Preprint

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We study the relaxation characteristics in the two-dimensional (l x × l y ) array of magnetic nanoparticles (MNPs) as a function of aspect ratio A r = l y /l x , dipolar interaction strength h d and anisotropy axis orientation using computer simulation. The anisotropy axes of all the MNPs are assumed to have the same direction, α being the orientational angle. Irrespective of α and A r , the functional form of the magnetization-decay curve is perfectly exponentially decaying with h d ≤ 0.2. There exists a transition in relaxation behaviour at h d ≈ 0.4; magnetization relaxes slowly for α ≤ 45 • ; it relaxes rapildy with α > 45 • . Interestingly, it decays rapidly for h d > 0.6, irrespective of α. It is because the dipolar interaction promotes antiferromagnetic coupling in such cases. There is a strong effect of α on the magnetic relaxation in the highly anisotropic system (A r ≥ 25). Interesting physics unfolds in the case of a huge aspect ratio A r = 400. There is a rapid decay of magnetization with α, even for weakly interacting MNPs. Remarkably, magnetization does not relax even with a moderate value of h d = 0.4 and α = 0 • because of ferromagnetic coupling dominance. Surprisingly, there is a complete magnetization reversal from saturation (+1) to −1 state with α > 60 • . The dipolar field and anisotropy axis tend to get aligned antiparallel to each other in such a case. The effective Néel relaxation time τ N depends weakly on α for small h d and A r ≤ 25.0. For large A r , there is a rapid fall in τ N as α is incremented from 0 to 90 • . These results benefit applications in data and energy storages where such controlled magnetization alignment and desired structural anisotropy are desirable.

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Enhanced magnetic performance of aligned wires assembled from nanoparticles: from nanoscale to macroscale

Cited by 5 publications

References 61 publications

Anisotropic Effect of Dipolar Interaction in Ordered Ensembles of Nanoparticles

Anisotropic Effect of Dipolar Interaction in Ordered Ensembles of Nanoparticles

Magnetostatic model for magnetic particle agregagates with cylindrical shapes

Relaxation in Ordered Assembly of Magnetic Nanoparticles

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