Magnetic nanowires as permanent magnet materials

Maurer, Thomas; Ott, F.; Chaboussant, Grégory; Soumare, Yaghoub; Piquemal, Jean‐Yves; Viau, Guillaume

doi:10.1063/1.2800786

Cited by 100 publications

(85 citation statements)

References 13 publications

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“…This latter value is expected for a standard Stoner-Wohlfarth model in the case of random-oriented nanowires (author?) [34]. In the case of FC hysteresis loops, the Mr M S ratio was usually≥ 0.6 and reached the value of ≈ 0.7 for the cylinder type nanowires (circle symbols), confirming the easier alignment for the nanowires with the highest coercivity (see inset 2 (a)).…”

Section: Nanowire Shape and Length Effectsmentioning

confidence: 59%

Morphology control of the magnetization reversal mechanism in Co80Ni20 nanomagnets

Mercone

Zighem

Léridon

et al. 2015

Journal of Applied Physics

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Nanowires with very different size, shape, morphology and crystal symmetry can give rise to a wide ensemble of magnetic behaviors whose optimization determines their applications in nanomagnets. We present here an experimental work on the shape and morphological dependence of the magnetization reversal mechanism in weakly interacting Co80Ni20 hexagonal-close-packed nanowires. Non-agglomerated nanowires (with length L and diameter d) with a controlled shape going from quasi perfect cylinders to diabolos, have been studied inside their polyol solution in order to avoid any oxidation process. The coercive field HC was found to follow a standard behavior and to be optimized for an aspect ratio L d > 15. Interestingly, an unexpected behavior was observed as function of the head morphology leading to the strange situation where a diabolo shaped nanowire is a better nanomagnet than a cylinder. This paradoxical behavior can be ascribed to the growth-competition between the aspect ratio L d and the head morphology ratio d D (D being the head width). Our experimental results clearly show the importance of the independent parameter (t = head thickness) that needs to be considered in addition to the shape aspect ratio ( L d ) in order to fully describe the nanomagnets magnetic behavior. Micromagnetic simulations well support the experimental results and bring important insights for future optimization of the nanomagnets morphology.

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Section: Nanowire Shape and Length Effectsmentioning

confidence: 59%

Morphology control of the magnetization reversal mechanism in Co80Ni20 nanomagnets

Mercone

Zighem

Léridon

et al. 2015

Journal of Applied Physics

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show abstract

“…Due to the absence of defects and to their mono--crystalline state, experimental coercivity can reach values larger than 0.5 T at room temperature. We showed in previous work that half of the observed coercivity could be accounted for by the magneto--crystalline anisotropy (Maurer 2007 andAit--Atmane 2013). The remaining part can be attributed to the shape anisotropy contribution.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the magnetic properties of aligned Co nanowires/polymer composites for the fabrication of permanent magnets

et al. 2014

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We aim at combining high coercivity magnetic nanowires in a polymer matrix in a view to fabricate rare--earth free bonded magnets. In particular, our aim is to fabricate anisotropic materials by aligning the wires in the polymer matrix. We have explored the different parameters of the fabrication process in order to produce a material with the best possible magnetic properties. We show that the choice of a proper solvent allows obtaining stable nanowire suspensions. The length and the type of the polymer chains play also an important role. Smaller chains (M w <10000) provide better magnetization results. The magnetic field applied during the casting of the material plays also a role and should be of the order of a fraction of a tesla. The local order of the nanowires in the matrix has been characterized by TEM and Small Angle Neutron Scattering. The correlation between the local order of the wires and the magnetic properties is discussed. Materials with coercivity µ 0 H c up to 0.70 T at room temperature have been obtained.2

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“…polyvinylpyrrolidone) and microwave heating, various types of nanoparticles have been synthetized . Metals (Ni [6,7], Co [8,9], Cu [10], Pd [11], Ag [12][13][14], Pt [15][16][17], Au, [18,19] ), alloys [9,[19][20][21][22][23][24][25], oxides (MgO, TiO 2 , ZnO, SnO 2 , Gd 2 O 3 , Fe oxides and ferrites, hydroxyapatite [26][27][28][29][30][31][32][33][34][35], metal-polymer nanocomposites [36], supported metal catalysts [37][38][39][40], have been designed.…”

Section: Direct Methods For the Preparation Of Nanoparticlesmentioning

confidence: 99%

“…Heterogeneous nucleation has also proved to be an efficient method for the control of the particle growth. Using Ruthenium as a seed (Ru is more easily reducible than cobalt or nickel), allows to get nickel-cobalt ( figure 3a) or cobalt (figure 3b) nanowires [16,17]. Note that the addition of a heterogeneous nucleating agent is critical since without Ru, only isotropic polycrystalline sub-micronic particles are obtained (see Figure 3 c).…”

Section: Control Of the Particle Shapementioning

confidence: 99%

Nanoparticles of metal and metal oxides: some peculiar synthesis methods, size and shape control, application to catalysts preparation

Bozon‐Verduraz¹,

Fiévet²,

Piquemal³

et al. 2009

Braz. J. Phys.

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One step (direct) and multisteps synthesis methods of metal and oxide nanoparticles are presented including both bottom-up and top-down procedures. Chemical methods involving the polyol process allows to get either isotropic or anisotropic nanoparticles. Nanowires, nanorods and dumbells can be generated either by heterogeneous nucleation or by using a template (mesoporous silica). Top-down procedures are illustrated by laser irradiation of immersed bulk targets (Ag, Au) which generates self-organized nanostructures or colloidal solutions. Laser irradiation of these colloidal solutions modifies the size distribution and the shape of nanoparticles. Bimetallic nanoparticles are generated from mixtures of monometallic colloidal solutions. Surface-mediated methods involving a host support and an invited phase are also presented. They lead to the formation of metal or oxide clusters and nanoparticles. The speciation of these entities is correlated with the observed catalytic performances.

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Magnetic nanowires as permanent magnet materials

Cited by 100 publications

References 13 publications

Morphology control of the magnetization reversal mechanism in Co80Ni20 nanomagnets

Morphology control of the magnetization reversal mechanism in Co80Ni20 nanomagnets

Optimization of the magnetic properties of aligned Co nanowires/polymer composites for the fabrication of permanent magnets

Nanoparticles of metal and metal oxides: some peculiar synthesis methods, size and shape control, application to catalysts preparation

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