Magnetic anisotropies and exchange coupling in ultrathin fcc Co(001) structures

Heinrich, B.; Cochran, J. F.; Kowalewski, M.; Kirschner, J.; Celiński, Z.; Arrott, A. S.; Myrtle, K.

doi:10.1103/physrevb.44.9348

Cited by 321 publications

(142 citation statements)

References 26 publications

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“…This refers in particular to films with perpendicular magnetic anisotropy, [1][2][3][4][5][6][7][8][9] whereas the main effect of magnetostatic interactions in films with easy-plane anisotropy is to confine the magnetization to the film plane. 10,11 To illustrate the difference, we approximate the thin film by a homogeneously magnetized ellipsoid of revolution of volume V whose radius R x ϭR y ϭR is much larger than the ''film thickness'' 2R z .…”

Section: ͑1͒mentioning

confidence: 99%

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Micromagnetics of ultrathin films with perpendicular magnetic anisotropy

1998

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Magnetization processes in ultrathin transition-metal films with perpendicular magnetic anisotropy are investigated. By model calculations it is shown that nucleation in ideal films is incoherent and therefore bulklike, whereas the truly ultrathin limit of coherent nucleation is restricted to film patches of small cross-section areas. In ideal monolayers, the nonzero film thickness leads to bulklike nucleation if the lateral dimensions of the film exceed about 1 m. This means that monolayer patches having submicrometer diameters cannot be regarded as ultrathin in a micromagnetic sense. On the other hand, the critical single-domain diameter of ultrathin films is larger by one order of magnitude than expected from bulk-type thin-film calculations.

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Section: ͑1͒mentioning

confidence: 99%

“…A fairly recent development is the deposition and investigation of ultrathin transition-metal films with perpendicular anisotropy. 1,7,9 It is now possible to produce nearly ideal ultrathin film patches having diameters of order 50 nm and containing more than 10 000 atoms ͑see, e.g., Ref. 13͒.…”

Section: ͑1͒mentioning

confidence: 99%

Micromagnetics of ultrathin films with perpendicular magnetic anisotropy

1998

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“…We focused our study on the effect of coupling on the characteristics of the different excited modes and we addressed the consequences of the nonlinear excitation resulting from the use of high amplitude and extremely short pulsed fields in such systems. The case of symmetrical exchange-coupled layers where the two ferromagnetic layers have the same thickness (here 30 nm) is less complicated compared to the asymmetrical layers and, in contrast to the symmetrical layers, it has been far less explored [6][7][8][9]. In these works, Brillouin light scattering and FMR have been used to determine the coupling constants and anisotropies in Co/Cu/Co [6] and Fe/Cu/Fe [7] asymmetrical layers without addressing the effect of the thickness difference between ferromagnetic layers on the mode frequency.…”

Section: Introductionmentioning

confidence: 99%

“…The case of symmetrical exchange-coupled layers where the two ferromagnetic layers have the same thickness (here 30 nm) is less complicated compared to the asymmetrical layers and, in contrast to the symmetrical layers, it has been far less explored [6][7][8][9]. In these works, Brillouin light scattering and FMR have been used to determine the coupling constants and anisotropies in Co/Cu/Co [6] and Fe/Cu/Fe [7] asymmetrical layers without addressing the effect of the thickness difference between ferromagnetic layers on the mode frequency. It is thus of great interest to see how this thickness difference between the two ferromagnetic coupled layers can affect the properties of the various modes.…”

Section: Introductionmentioning

confidence: 99%

Microwave spectroscopy with vector network analyzer for interlayer exchange-coupled symmetrical and asymmetrical NiFe/Ru/NiFe

Belmeguenai¹,

Martin²,

Woltersdorf³

et al. 2008

J. Phys.: Condens. Matter

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Vector network analyzer ferromagnetic resonance spectroscopy (VNA-FMR) is used here to study the different excited modes of sputtered asymmetrical NiFe(13.6 nm)/Ru(d Ru )/ NiFe(27.2 nm) exchange-coupled films with variable Ru thicknesses. The obtained results have been compared to those of the symmetrical NiFe(30 nm)/Ru(d Ru )/NiFe(30 nm). In both cases, the measurements show the existence of an optic and an acoustic precessional mode. The optic mode was only observed over limited field ranges, especially in the symmetrical trilayers. To overcome such a limitation, we developed a new technique similar to the longitudinal FMR, where the bias and the rf field are parallel to each other and perpendicular to the pinning field. Interestingly, and in contrast to the symmetrical trilayers, we observed a mode anti-crossing in the dispersion relation of the asymmetrical layers that we attributed to the thickness difference between the two NiFe layers. Our experimental results on the effect of the biquadratic coupling on the mode frequency variations are in good agreement with the theory.

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“…14 For our experimental studies of the effect of roughness on the magnetic properties of thin epitaxial films, we chose to investigate fcc Co layers grown on Cu͑001͒/Si͑001͒. This is a well studied and characterized system, [15][16][17] allowing us to directly relate any observed changes in magnetic behavior to the morphology of the film. By modeling the roughness contribution to the effective magnetocrystalline anisotropy constants, we are able to explain the observed decrease in anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Effect of substrate roughness on the magnetic properties of thin fcc Co films

et al. 2007

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We present a study of the influence of substrate roughness on the magnetic properties of thin fcc Co films ͑7 and 17 nm thick͒ grown on Cu͑001͒/Si͑001͒. A significant decrease in cubic anisotropy with increasing film roughness was observed with Brillouin light scattering and magneto-optical Kerr effect magnetometry. In addition, the rougher samples showed a substantial broadening of the spin wave peaks. Both effects were found to be more pronounced for the thinner Co layers. Our observations are discussed in the framework of a theoretical model which takes into account the morphology of the Co films as measured by atomic force microscopy. While roughness effects are usually discussed in the context of Néel's "orange-peel" model, we propose a qualitatively different effect in this work whereby the magnetization follows coherently the substrate morphology ͑"undulating" state͒ resulting in the absence of magnetic surface charges. This magnetic configuration gives rise to a reduction in the magnetic anisotropy of epitaxial thin films, which is in good qualitative agreement with the experimental observations.

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Magnetic anisotropies and exchange coupling in ultrathin fcc Co(001) structures

Cited by 321 publications

References 26 publications

Micromagnetics of ultrathin films with perpendicular magnetic anisotropy

Micromagnetics of ultrathin films with perpendicular magnetic anisotropy

Microwave spectroscopy with vector network analyzer for interlayer exchange-coupled symmetrical and asymmetrical NiFe/Ru/NiFe

Effect of substrate roughness on the magnetic properties of thin fcc Co films

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