Spin-glasslike behavior of magnetic ordered state originating from strong interparticle magnetostatic interaction in α-Fe nanoparticle agglomerate

Hiroi, Kosuke; Kura, Hiroaki; Ogawa, Tomoyuki; Takahashi, M.; Sato, Tetsuya

doi:10.1063/1.3602313

Cited by 27 publications

(14 citation statements)

References 21 publications

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“…The memory effects in the zero field-cooled dc susceptibility at high temperature together with the flatness of the associated field-cooled curve below a characteristic temperature are indentifying features of the peculiar properties of a superspin glass system [118,119]. Similar characteristics have been also observed for nanocrystal assemblies with 35% [54] and 44% [56] magnetic material volume fractions. The memory effects at low temperature are accompanied by a spin glass freezing due to the surface defect environment of the incorporated nanocrystals [52,[121][122][123].…”

Section: Spin Glass Behavior and Cooperative Microscopic Mechanismssupporting

confidence: 56%

“…In the case, though, where these nanocrystals assemble in a nanocluster-like structure, a collective magnetic behavior is likely to emerge. In terms of the inter-particle dipole-dipole interactions involved, the new larger entity may entail [49][50][51]: (i) a superparamagnetic character for non-or weakly-interacting particles (low dipolar interaction strength, g) [52], and (ii) a superspin glass for strongly interacting particles (high g) [53][54][55][56], which is a behavior analogous to a canonical spin glass. When the inter-particle interactions are very strong, the superspin moments are coupled ferromagnetically, and the assemblies are called superferromagnetic [57].…”

Section: Introductionmentioning

confidence: 99%

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Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Κωστοπούλου

Lappas

2015

Nanotechnology Reviews

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Magnetic particles of optimized nanoscale dimensions can be utilized as building blocks to generate colloidal nanocrystal assemblies with controlled size, well-defined morphology, and tailored properties. Recent advances in the state-of-the-art surfactant-assisted approaches for the directed aggregation of inorganic nanocrystals into cluster-like entities are discussed, and the synthesis parameters that determine their geometrical arrangement are highlighted. This review pays attention to the enhanced physical properties of iron oxide nanoclusters, while it also points to their emerging collective magnetic response. The current progress in experiment and theory for evaluating the strength and the role of intra-and inter-cluster interactions is analyzed in view of the spatial arrangement of the component nanocrystals. Numerous approaches have been proposed for the critical role of dipole-dipole and exchange interactions in establishing the nature of the nanoclusters' cooperative magnetic behavior (be it ferromagnetic or spin-glass like). Finally, we point out why the purposeful engineering of the nanoclusters' magnetic characteristics, including their surface functionality, may facilitate their use in diverse technological sectors ranging from nanomedicine and photonics to catalysis.

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Section: Spin Glass Behavior and Cooperative Microscopic Mechanismssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Κωστοπούλου

Lappas

2015

Nanotechnology Reviews

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“…Some of the commonly observed size effects are lowering of saturation magnetization, increase in coercivity, surface spin canting, exchange anisotropy and inter particle interactions [12][13][14][15][16][17]. Particle size and size distribution are known to be sensitive to the processing techniques/conditions and is one of the main challenges in the synthesis of nano-sized particles.…”

Section: Introductionmentioning

confidence: 98%

Investigation of structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nano powders prepared by self combustion method

Sudheesh

Nehra

Vinesh

et al. 2013

Materials Research Bulletin

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“…Spin-glass arises in magnetic systems due to randomness and frustration of magnetic spins. There can be two kinds of spin-glass behavior in nanoparticles, one is the super spin-glass [9][10][11] which arises in interacting nanoparticles due to random freezing of the huge core spin (super spin) of individual nanoparticles, while second is the surface spinglass in core/shell nanoparticles due to disordered surface spins [12,13]. The memory effect (ME) is reported also for non-interacting superparamagnetic nanoparticles due to distribution in their relaxation times which arises through particle size distribution [14].…”

Section: Introductionmentioning

confidence: 99%

Memory effect versus exchange bias for maghemite nanoparticles

Nadeem

Krenn

Szabó

2015

Journal of Magnetism and Magnetic Materials

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a b s t r a c tWe studied the temperature dependence of memory and exchange bias effects and their dependence on each other in maghemite (γ-Fe 2 O 3 ) nanoparticles by using magnetization studies. Memory effect in zero field cooled process in nanoparticles is a fingerprint of spin-glass behavior which can be due to i) surface disordered spins (surface spin-glass) and/or ii) randomly frozen and interacting nanoparticles core spins (super spin-glass). Temperature region (25-70 K) for measurements has been chosen just below the average blocking temperature (T B ¼75 K) of the nanoparticles. Memory effect (ME) shows a nonmonotonous behavior with temperature. It shows a decreasing trend with decreasing temperature and nearly vanishes below 30 K. However it also decreased again near the blocking temperature of the nanoparticles e.g., 70 K. Exchange bias (EB) in these nanoparticles arises due to core/shell interface interactions. The EB increases sharply below 30 K due to increase in core/shell interactions, while ME starts vanishing below 30 K. We conclude that the core/shell interface interactions or EB have not enhanced the ME but may reduce it in these nanoparticles.

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Spin-glasslike behavior of magnetic ordered state originating from strong interparticle magnetostatic interaction in α-Fe nanoparticle agglomerate

Abstract: Influence of excess Fe accumulation over the surface of FePt nanoparticles: Structural and magnetic properties

Cited by 27 publications

References 21 publications

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Investigation of structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nano powders prepared by self combustion method

Memory effect versus exchange bias for maghemite nanoparticles

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