Exchange bias in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mtext>Fe</mml:mtext><mml:mo>/</mml:mo><mml:msub><mml:mrow><mml:mtext>Fe</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>core-shell magnetic nanoparticles mediated by frozen interfacial spins

Ong, Quy K.; Wei, Alexander; Lin, Xiao‐Min

doi:10.1103/physrevb.80.134418

Cited by 120 publications

(91 citation statements)

References 36 publications

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“…This is consistent with the hypothesis that only a small fraction of interfacial spins control the exchange bias. 30,39 A second indirect consideration is the low saturation magnetization of the system due to the high Co-oxide content compared to samples 3 and 4, which results in the amplification of exchange bias. 33 However, the reduction of exchange bias when the temperature drops below 50 K is not clear at present.…”

Section: Magnetic Characterizationmentioning

confidence: 99%

Morphology influence on nanoscale magnetism of Co nanoparticles: Experimental and theoretical aspects of exchange bias

et al. 2011

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Co-based nanostructures ranging from core/shell to hollow nanoparticles were prepared by varying the reaction time and the chemical environment during the thermal decomposition of Co 2 (CO) 8 . Both structural characterization and kinetic model simulation illustrate that the diffusivities of cobalt and oxygen determine the growth ratio and the final morphology of the nanoparticles. Exchange coupling between Co and Co-oxide in core/shell nanoparticles induced a shift of field-cooled hysteresis loops that is proportional to the shell thickness, as verified by numerical studies. The increasing nanocomplexity, when passing from core/shell to hollow particles, also leads to the appearance of hysteresis above 300 K due to an enhancement of the surface anisotropy resulting from the additional spin-disordered surfaces.

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Section: Magnetic Characterizationmentioning

confidence: 99%

Morphology influence on nanoscale magnetism of Co nanoparticles: Experimental and theoretical aspects of exchange bias

et al. 2011

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“…Recent experiments have also demonstrated EB in the case of samples having a FM layer in contact with a spin glass layer 12,13 ; layered nanoparticle/ferromagnetic structures where various models have been suggested to explain the origin of EB 14 . Core-shell nanoparticles with a conventional FM (core)/AFM (shell) and more recently "inverted" AFM (core)/FM (shell) have also been studied and the general consensus to explain EB is the freezing of interfacial spins or the growth of droplets with uncompensated spins [15][16][17] .…”

Section: Introductionmentioning

confidence: 99%

Spin dynamics and criteria for onset of exchange bias in superspin glass Fe/γ-Fe2O3core-shell nanoparticles

Chandra

Khurshid

et al. 2012

Phys. Rev. B

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“…[17][18][19][20][21][22][23][24][25] In this situation, strong exchange magnetic coupling between the iron particle core and the iron oxide shell gives rise to modifications in the coercivity, the magnetic anisotropy, and to the appearance of an exchange-bias ͑EB͒ effect. [26][27][28][29][30][31][32][33][34][35] This phenomenology is mostly observed in thin films composed of alternating ferromagnetic/antiferromagnetic ͑FM/AFM͒ layers when the Néel temperature ͑T N ͒ of the AFM layer is smaller than the Curie temperature ͑T C ͒ of the FM one. In order to minimize the exchange energy at the interface, the magnetic moments of both FM and AFM layers become coupled, thus giving rise to an effective uniaxial anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and magnetism of nanoparticles withγ-Fecore surrounded byα-Feand iron oxide shells

et al. 2010

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Iron-carbon nanocomposites have been elaborated by means of a simple chemical procedure based on in situ synthesis of iron nanoparticles within the nanopores of an activated carbon. The Fe nanoparticles present a broad particle-size distribution ͑5-40 nm͒. A combined structural and magnetic study seems to suggest that most of the nanoparticles of mean size ϳ15 nm have exotic "onionlike" core-shell morphology of ␥-Fe nucleus surrounded by a concentric double shell of ␣-Fe and maghemitelike oxide. The true nature of Fe-oxide was successfully evidenced through room temperature x-ray absorption spectroscopy. The whole system does not reach a fully superparamagnetic regime even at 750 K, probably due to higher blocking temperatures for the largest nanoparticles. Mössbauer spectrometry indicates that low temperature para-to-antiferromagnetic transition for the ␥-Fe phase cannot be discarded. In addition, the external Fe-oxide shell exhibits spin-glass behavior giving rise to the freezing of its magnetic moments at low temperatures. Hence, we propose a competing double magnetic coupling: ͑i͒ the oxide shell/␣-Fe interaction and ͑ii͒ the possible antiferromagnetic coupling between ␥-Fe nucleus and ␣-Fe layer; as being both responsible for the observed exchange bias effect at T =5 K ͑H ex Ϸ 150 Oe͒.

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Exchange bias inFe/Fe3O4core-shell magnetic nanoparticles mediated by frozen interfacial spins

Cited by 120 publications

References 36 publications

Morphology influence on nanoscale magnetism of Co nanoparticles: Experimental and theoretical aspects of exchange bias

Morphology influence on nanoscale magnetism of Co nanoparticles: Experimental and theoretical aspects of exchange bias

Spin dynamics and criteria for onset of exchange bias in superspin glass Fe/γ-Fe2O3core-shell nanoparticles

Microstructure and magnetism of nanoparticles withγ-Fecore surrounded byα-Feand iron oxide shells

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