Co–CoO nanoparticles prepared by reactive gas-phase aggregation

González, Javier; Andrés, J. P.; Toro, J. A. De; Muniz, Pablo Rodrigues; Muñoz, T.; Crisan, O.; Binns, C.; Riveiro, José Manuel Suárez

doi:10.1007/s11051-008-9576-8

Cited by 30 publications

(26 citation statements)

References 24 publications

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“…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. We tentatively attribute this effect to a slight canting of the Co 2+ spins at the tetrahedral sites within the Co 3 O 4 .…”

Section: Magnetic Characterizationmentioning

confidence: 90%

“…The transition from zero magnetization to the rapidly increasing part is described as the exchange-bias onset temperature. 33 After this point the FM/AFM coupling begins to gradually disappear. Experimentally, we also find a sudden rise of ZFC-FC magnetization below 33 K, attributed to traces of Co 3 Noteworthy, the corresponding ZFC-FC curves of samples 3 and 4 [Figs.…”

Section: Magnetic Characterizationmentioning

confidence: 99%

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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: 90%

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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“…1,3,5 Due to its appealing properties (e.g., a large interface energy, γ) one of the most studied FM/AFM core/shell systems is Co/CoO. [30][31][32][33][34][35][36][37][38][39][40][41][42] Interestingly, in this system H E values ranging from a few to thousands of Oe have been reported for relatively similar nanoparticles. Several effects have been reported to influence HE in Co/CoO: core diameter, 34,39,40 shell thickness, 34,37,39,40 crystallinity of the shell, 32,43,44 exchange interactions with neighboring particles, 32,45 strains, 34 orbital moments, 45 uncompensated spins 33,41 and the matrix they are embedded in (through lattice matching effects or antiferromagnetic proximity effects).…”

Section: Introductionmentioning

confidence: 99%

Maximizing Exchange Bias in Co/CoO Core/Shell Nanoparticles by Lattice Matching between the Shell and the Embedding Matrix

et al. 2017

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The exchange bias properties of 5 nm Co/CoO ferromagnetic/antiferromagnetic core/shell nanoparticles, highly dispersed in a CuxO matrix, have been optimized by matching the lattice parameter of the matrix with that of the CoO shell. Exchange bias and coercivity fields as large as HE = 7780 Oe and HC = 6950 Oe are linked to the presence of a Cu2O matrix (0.3% lattice mismatch with respect to the shells). The small mismatch between Cu2O and CoO plays a dual role, (i) structurally stabilizing the CoO and (ii) favoring the existence of a large amount of uncompensated moments in the shell that enhance the exchange bias effects. The results evidence that lattice matching may be a very efficient way to improve the exchange bias properties of core/shell nanoparticles, paving the way to novel approaches to tune their magnetic properties.

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“…Lately, besides the colloidal bimetallic core-shell NP's, another approach undertaken was to use surface-functionalized nanoclusters (NC's) obtained using a novel gas-stabilized cluster aggregation method [18]. Whereas the choice of colloidal core-shell NP's systems is limited by the composition of the organo-metallic precursors, used for the colloidal synthesis procedures, to only several bimetallic options (AgCo, FePt, FePd, CoPt, MnPt) the gas-phase aggregation method has the versatility of obtaining complex alloyed, core -multiple shells NC's with tightly controlled core size and shell thickness and, moreover, free choice of materials in the core and shells, from exchange bias Fe / Fe oxide [19] and Co / CoO [20] to Fe / Si luminescent clusters [21]. We propose in the current paper to create a hybrid architecture structure where a logic conditioned interdigitated die is used to support the magnetic nanomaterial and arrange it into a logic integrated platform and we demonstrate its functionality as spintronic and sensing device by detection of significant magnetoresistive signal along metallic conductive predefined interdigits.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Nanoelectronic-magnetic Device with Magnetoresistive Effect for logic integrated platforms in Spintronics

Crisan¹,

Crisan²,

Luculescu³

2019

Preprint

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We propose a concept of hybrid nanoelectronic-magnetic device for logic integrated platforms made of magnetic core-shell nanoparticles deposited onto prepatterned Si (111) substrate with basic logic circuitry made of metallic conductive lines. The synthesis of magnetic material and the creation of nanoelectronic prepatterned interdigitated die is reported and its capabilities are demonstrated in terms of magnetotransport properties. The laser pyrolysis method is employed in order to synthesize magnetic core-shell Fe / FeC nanoparticles with sizes between 12 – 15 nm. E-beam lithography has been used in order to design and execute two different layouts of interdigitated die, prepatterned with logic capacity, one with two pads and 50 microns thick conductive metallic lines, another one with 4 pads and parallel 5 microns thick conductive lines separated by 5 microns thick spacer. The as-obtained structures are morphologically characterized by means of optical, scanning and transmission electron microscopies. As-synthesized core-shell nanoparticles have been magnetically characterized inasmuch as the hybrid device obtained by depositing centrifugated and dispersed core-shell nanoparticles from liquid carrier solutions. For the first time, a significant giant magnetoresistive (GMR) effect has been observed and measured for the hybrid architectured device made of Fe / FeC nanosized materials on pre-patterned interdigitated die. A ∆R/R of 8% at 4.2 K has been measured from conductivity-in-plane electron transport measurements. This opens possibilities for the use of such devices as arrays of nanosensors and in spintronic applications.

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Co–CoO nanoparticles prepared by reactive gas-phase aggregation

Cited by 30 publications

References 24 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

Maximizing Exchange Bias in Co/CoO Core/Shell Nanoparticles by Lattice Matching between the Shell and the Embedding Matrix

Hybrid Nanoelectronic-magnetic Device with Magnetoresistive Effect for logic integrated platforms in Spintronics

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