Magnetic microstructures from magnetic force microscopy and Monte Carlo simulation in CoFe-Ag-Cu granular films

Franco, V.; Batlle, X.; Valencia, A.; Labarta, A.; O'Grady, K.; Watson, Mark L.

doi:10.1109/20.706309

Cited by 15 publications

(15 citation statements)

References 13 publications

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“…Therefore, when magnetic particles are close to each other ͑at distances between particle surfaces smaller than about 1.5 nm at x v у0.25), interparticle interactions stabilize an out-of-plane stripe-like magnetic domain microstructure. 5,27 This result led us to conclude that magnetic percolation takes place well below the volume percolation threshold. Consequently, the remanent state after in-plane saturation displays an out-of-plane component of the magnetization, which does not contribute to the in-plane remanence.…”

Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 83%

“…28 An axial distortion larger than 0.01% is at least needed to induce significant uniaxial anisotropy. 24 5 either through the metallic matrix aided by the diluted paramagnetic atoms 29 or because the matrix itself becomes a weak ferromagnet 30 acting to couple the FM particles. Therefore, when magnetic particles are close to each other ͑at distances between particle surfaces smaller than about 1.5 nm at x v у0.25), interparticle interactions stabilize an out-of-plane stripe-like magnetic domain microstructure.…”

Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 99%

“…4͑c͒ and 4͑d͔͒ has to be attributable to the large size of the FM particles rather than to interparticle interactions. In addition, as the CoFe spins diluted in the matrix are completely segregated and the perpendicular anisotropy is removed, no out-of-plane component of the magnetization is observed in the annealed samples, 5,27 suggesting the formation of large in-plane domains. Consequently, no reduction in the remanence is observed.…”

Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 99%

“…5 At Tϭ0 K, the StonerWohlfarth model 6 predicts that the remanence-to-saturation magnetization ratio, M r /M s , is 0.5 for a random distribution of noninteracting uniaxial single domain particles with coherent rotation of the total magnetization. However, deviations from this ideal value are observed in real systems due to interparticle interactions and textured growth.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Remanence breakdown in granular alloys at magnetic percolation

Batlle

Franco

Labarta

et al. 2000

Journal of Applied Physics

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Microstructural effects on the magnetic behavior of rf-sputtered CoFe-AgCu granular alloys are examined through the study of the in-plane remanence-to-saturation magnetization ratio, M r /M s , as a function of temperature, ferromagnetic volume content, x v , and annealing temperature. At low ferromagnetic contents (x v р0.25), the M r M s ratio in as-deposited samples tends towards 0.5 at low temperature, as expected from the uniaxial perpendicular anisotropy displayed by all samples, which is magnetoelastic in nature and arises from the axial distortion of the CoFe face-centered-cubic cells. In as-deposited samples with x v Ͼ0.25 ͑well below the volume percolation threshold, x p ϳ0.5-0.55), a collective magnetic behavior develops due to magnetic correlations among particles. Consequently, a domain structure perpendicular to the film plane appears, which results in a remanence breakdown: M r /M s is about 0.2. Besides, magnetic correlations prevents the thermal decay of M r /M s , which is almost constant between 5 and 300 K, even for ferromagnetic particles no more than 3 nm in size. The axial distortion disappears with annealing, the cubic symmetry is recovered, the out-of-plane magnetic structure is lost and, therefore, the M r /M s ratio at low temperature tends towards 0.8 for highly annealed samples. Consequently, the magnetic properties of granular alloys depend on the interplay between anisotropy, exchange, and dipolar interactions, which in turn depend crucially on the microstructure.

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Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 83%

Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 99%

Section: B Temperature Decay Of the Remanence And Low Field Susceptimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Remanence breakdown in granular alloys at magnetic percolation

Batlle

Franco

Labarta

et al. 2000

Journal of Applied Physics

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“…[6][7][8][9][10][11][12] The exchange interaction may lead to structures in the form of stripes in which neighboring stripes correspond to the magnetic moments being oriented in different directions, provided that the interaction exceeds a certain threshold. 8 Also, interesting features in the in-plane to out-of-plane reorientation transitions have been observed experimentally 10 and by numerical simulations. 11 These features include the passing through of intermediate states of magnetic alignments in the form of stripes as a system relaxes to its equilibrium magnetic moment configuration.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium magnetic moment configurations in magnetic nanoparticle films: Effects of anisotropy, dipolar interaction, and Zeeman energy

Hui

2005

Journal of Applied Physics

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The equilibrium configurations of films consisting of magnetic small particles in which the anisotropy energy tends to align the magnetic moments perpendicular to the film are studied by Monte Carlo simulations. The effects of anisotropy energy, dipolar interaction, and Zeeman energy due to an external applied magnetic field, which can either be perpendicular or parallel to the film, are considered. As the relative strength of the relevant interaction energies changes, the system exhibits a variety of different magnetic moment configurations. Due to the competition between the dipolar interaction energy and the anisotropy energy, it is found that an approximately antiferromagnetic alignment with moments oriented perpendicular to the film results when the anisotropy energy dominates; while an in-plane antiferromagnetic alignment results when the dipolar interaction energy dominates. Results obtained by a zero-temperature analysis based on energy minimization are found to be in qualitative agreement with results obtained by numerical simulations.

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