Disordered Magnetism at the Grain Boundary of Pure Nanocrystalline Iron

Bonetti, E.; Bianco, L. Del; Fiorani, D.; Rinaldi, D.; Caciuffo, R.; Hernando, A.

doi:10.1103/physrevlett.83.2829

Cited by 141 publications

(94 citation statements)

References 27 publications

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“…1(b)) reveals the frequency dispersion of the signal more distinctly, albeit at a lower temperature of around 160 K. It is rather a common feature that the peak in χ ′′ 1 appears at a lower temperature than the same in the χ ′ 1 , and has been observed in many well-known systems [18][19][20] , but the temperature difference here (≈ 30 K) seems to be unusually large. However, even such behavior has been observed earlier 21 , especially in systems with coexisting ferromagnetic and spin-glass features, appearing from the grains and the disordered grain boundaries, respectively 22 . It is to be noted that the ferromagnetic T c of Sr 2 FeMoO 6 lies well above 400 K and therefore, this low temperature transition can only be associated with a coexisting metastability in the sample, arising from a very different magnetic origin.…”

Section: Resultsmentioning

confidence: 80%

Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Ray

Middey

Jana

et al. 2011

EPL

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The unusual magnetoresistance (M R) behavior in Sr 2 FeMoO 6 , recently termed as spin-valve type MR (SVMR), presents several anomalies that are little understood so far. The difficulty in probing the origin of this phenomenon, arising from the magnetic property of only a small volume fraction of the ferromagnetic bulk, is circumvented in the present study by the use of ac susceptibility measurements that are sensitive to the slope rather than the magnitude of the magnetization. The present study unravels a spin-glass (SG) like surface layer around each soft ferromagnetic (FM) grain of Sr 2 FeMoO 6 . It is also observed that there is a very strong exchange coupling between the two, generating 'exchange bias' effect, which consequently creates the 'valve', responsible for the unusual M R effects.

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Section: Resultsmentioning

confidence: 80%

Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Ray

Middey

Jana

et al. 2011

EPL

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“…The techniques of inert gas condensation, [3,[47][48][49][50] pulsed plasma deposition, [25] and sputtering [48] have exclusively been used for processing thin films or small amounts of nanocrystalline materials, whereas it is necessary to produce/process bulk samples for oxidation/corrosion or mechanical testing. Electrodeposition [33,34,51] and severe plastic deformation [28][29][30][31][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] have been recognized as the two relatively successful routes for processing thicker/larger sections of nanocrystalline metals and alloys. Pulsed electrodeposition has been employed successfully for processing nanocrystalline materials in bulk, [51] most notably, Ni-Fe and Ni-Co alloys.…”

Section: B Synthesis Of Nanocrystalline Alloysmentioning

confidence: 99%

Role of Nanostructure in Electrochemical Corrosion and High Temperature Oxidation: A Review

Mahesh

Raman

2014

Metall Mater Trans A

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The extremely fine grain size of nanocrystalline (nc) metallic alloys results in significantly different mechanical, electrochemical and oxidation properties as compared to the coarse-grained alloys of the same composition. Although the synthesis and attractive mechanical properties of nanocrystalline materials have been investigated and reviewed in great depth, the high temperature oxidation and electrochemical corrosion of these materials has received limited attention. The difference in the active dissolution and passivation behavior of nc alloys as compared to their microcrystalline counterparts varies for each alloy system. However, a unified theory explaining these phenomena still eludes us. In this context, this article reviews the progress in the electrochemical corrosion behavior of different nanocrystalline alloys, and hence, develops a better understanding of the effect of grain size, composition, interfacial phenomena and selective dissolution on corrosion of nanocrystalline alloys. This review also presents the role of nanometric grain size and the associated increase in grain boundary diffusion on the high temperature oxidation of nc alloys. The attractive possibility of enhanced oxidation resistance at lower alloying additions as compared to the coarse-grained alloys has been discussed. Although the primary focus of the article is on ferrous alloy systems, however, the lead studies on the role of ultrafine grain size in oxidation/corrosion behavior of other alloys systems have also been reviewed.

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“…Peculiarly, in the case rϾr c -as a tribute to intrinsic randomness-reentrance into a SSG phase is encountered at low temperatures similarly as in amorphous 13 and nanocrystalline 14 FM materials. It is argued in this case that SSG and SFM ordering takes place on different percolating clusters, thus establishing the coexistence of two phases.…”

Section: Introductionmentioning

confidence: 99%

Interacting ferromagnetic nanoparticles in discontinuousCo80Fe20/A
Kleemann¹,
Petracic²,
Binek³
et al. 2001
Phys. Rev. B
200
11
151
1
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Dipolar superferromagnetism with reentrant low-temperature superspin glass behavior is observed on a randomly distributed ferromagnetic nanoparticle systems in discontinuous metal-insulator multilayers ͓Co 80 Fe 20 (t)/Al 2 O 3 ͑3 nm͔͒ 10 with nominal thickness 1.1рtр1.3 nm by use of ac susceptometry and dc magnetometry. At tϭ1.0 nm, superspin glass-like freezing is evidenced by the criticality of dynamic and nonlinear susceptibilities.

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Disordered Magnetism at the Grain Boundary of Pure Nanocrystalline Iron

Cited by 141 publications

References 27 publications

Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Role of Nanostructure in Electrochemical Corrosion and High Temperature Oxidation: A Review

Interacting ferromagnetic nanoparticles in discontinuousCo80Fe20/A
Kleemann¹,
Petracic²,
Binek³
et al. 2001
Phys. Rev. B
200
11
151
1
View full text Add to dashboard Cite

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Disordered Magnetism at the Grain Boundary of Pure Nanocrystalline Iron

Cited by 141 publications

References 27 publications

Origin of the unconventional magnetoresistance in Sr 2 FeMoO 6

Origin of the unconventional magnetoresistance in Sr 2 FeMoO 6

Role of Nanostructure in Electrochemical Corrosion and High Temperature Oxidation: A Review

Interacting ferromagnetic nanoparticles in discontinuousCo80Fe20/AKleemann1, Petracic2, Binek3 et al. 2001Phys. Rev. B200111511View full textAdd to dashboardCite

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Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Origin of the unconventional magnetoresistance in Sr ₂ FeMoO ₆

Interacting ferromagnetic nanoparticles in discontinuousCo80Fe20/A
Kleemann¹,
Petracic²,
Binek³
et al. 2001
Phys. Rev. B
200
11
151
1
View full text Add to dashboard Cite