Studies of coupled metallic magnetic thin-film trilayers

Rezende, S. M.; Chesman, C.; Lucena, M. A.; Azevedo, A.; Aguiar, F. M. de; Parkin, S. S. P.

doi:10.1063/1.368161

Cited by 113 publications

(92 citation statements)

References 32 publications

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“…If the energy of the optical mode is lower than that of the acoustic mode, the spin-wave spectrum has a reversed mode order. Mode order reversal in the spin-wave spectrum occurs as a consequence of AFM (exchange or dipolar) interaction between neighbouring magnetic layers and as such is widely discussed in the literature [42][43][44][45][46][47][48]. Here we demonstrate that in in-plane propagation the mode order can be reversed even if both the NN and NNN interactions are ferromagnetic.…”

Section: Introductionmentioning

confidence: 61%

Dynamic effects on the spin-wave spectrum of the bcc thin film

Mamica

2014

Eur. Phys. J. B

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Abstract. In the present paper we consider a ferromagnetic thin film with exchange interaction between nearest and next-nearest neighbours. Using a microscopic model based on the Heisenberg Hamiltonian we investigate how the propagation parallel to the surface of the film affects the spin-wave spectrum. Due to its wave-vector dependence the effective coupling between lattice planes parallel to the surface can be of ferromagnetic or antiferromagnetic character, or it can vanish completely, depending on the propagation of spin waves. When the effective coupling vanishes, the film separates into subsystems in which spin waves propagate independently. Antiferromagnetic effective coupling for certain wave vectors implies reversed mode order in the spectrum (with the optical mode at the bottom and the acoustic one at the top). Interestingly, this effect occurs also when all the exchange interactions in the considered system are ferromagnetic.

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Section: Introductionmentioning

confidence: 61%

Dynamic effects on the spin-wave spectrum of the bcc thin film

Mamica

2014

Eur. Phys. J. B

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“…The virtual multilayer consisting of the virtual ferromagnetic sheets is then treated within the conventional UTFA approach. 10,22,23,24 It is of crucial importance to divide the ferromagnetic layers into thin enough sheets in order to obtain (i) the correct ground state for the case of strong interlayer coupling or (ii) the frequencies of modes, which are not uniform in the perpendicular direction, i.e.…”

Section: Calculationmentioning

confidence: 99%

“…Only three publications 10,11,13 employ the much easier ultrathin film approximation (UTFA), 10,22,23,24 which has been thought to be accurate only for the lowest-energy modes of ferromagnetic films with thicknesses well below the exchange length, i.e. a few nanometers in the case of Fe.…”

Section: Introductionmentioning

confidence: 99%

Intensity of Brillouin light scattering from spin waves in magnetic multilayers with noncollinear spin configurations: Theory and experiment

et al. 2007

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The scattering of photons from spin waves (Brillouin light scattering -BLS) is a well-established technique for the study of layered magnetic systems. The information about the magnetic state and properties of the sample is contained in the frequency position, width, and intensity of the BLS peaks. Previously [Phys. Rev. B 67, 184404 (2003)], we have shown that spin wave frequencies can be conveniently calculated within the ultrathin film approach, treating the intralayer exchange as an effective bilinear interlayer coupling between thin virtual sheets of the ferromagnetic layers.Here we give the consequent extension of this approach to the calculation of the Brillouin light scattering (BLS) peak intensities. Given the very close relation of the BLS cross-section to the magneto-optic Kerr effect (MOKE), the depth-resolved longitudinal and polar MOKE coefficients calculated numerically via the usual magneto-optic formalism can be employed in combination with the spin wave precessional amplitudes to calculate full BLS spectra for a given magnetic system. This approach allows an easy calculation of BLS intensities even for noncollinear spin configurations including the exchange modes. The formalism is applied to a Fe/Cr/Fe/Ag/Fe trilayer system with one antiferromagnetically coupling spacer (Cr). Good agreement with the experimental spectra is found for a wide variety of spin configurations.

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“…The operation point of a spin valve sensor depends directly on the magnetic coupling between the two FM layers [2]. Ferromagnetic resonance (FMR) has been shown to be the most successful technique to determine the values of the effective fields associated to the couplings between the various layers in magnetic multilayer systems [3][4][5]. We investigate the competition between the exchange bias coupling and the interlayer exchange coupling, in spin valve systems and present a calculation of the spin wave dispersion relation in these systems that can be used to interpret the in-plane ferromagnetic resonance field dependence.…”

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confidence: 99%

Ferromagnetic resonance dispersion relation of spin valve systems

Rodrı́guez-Suárez

Rezende

Azevedo

2005

phys. stat. sol. (c)

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PACS 75.30.Ds, 76.50.+g We derive the FMR dispersion relation of spin valve systems taking into account the competition that can appears between the direct exchange bias coupling and the indirect interlayer coupling. For uncoupled ferromagnetic (FM) layers, the system exhibits a dispersion relation corresponding to two independent systems: a single FM layer (free layer) and an exchange-coupled bilayer (reference/antiferromagnetic layers). In the interlayer coupled regime a unidirectional anisotropy is induced in the free layer and the FMR field is overall downshifted.Magnetic spin valves [1] have been widely investigated since the discovery of their magnetic properties and the realization of their potential applications as magnetoresistive sensor in magnetic read/write heads of storage devices [2] and in magnetoresistive random access memories (MRAM). A spin valve consists of two ferromagnetic (FM) metal layers separated by a thin nonmagnetic metal layer, in atomic contact with a thick antiferromagnetic (AF) layer. The first FM film, named reference layer, has the direction of its magnetization set in a fixed direction by the exchange bias coupling with the AF layer. The magnetization of the other FM layer is free to rotate in response to an in-plane external magnetic field. The operation point of a spin valve sensor depends directly on the magnetic coupling between the two FM layers [2]. Ferromagnetic resonance (FMR) has been shown to be the most successful technique to determine the values of the effective fields associated to the couplings between the various layers in magnetic multilayer systems [3][4][5]. We investigate the competition between the exchange bias coupling and the interlayer exchange coupling, in spin valve systems and present a calculation of the spin wave dispersion relation in these systems that can be used to interpret the in-plane ferromagnetic resonance field dependence. We consider three coupled magnetic layers denoted by FM 1 (free layer), FM 2 (reference layer) and AF 3 (antiferromagnetic). The magnetization vectors for the three layers are given by 1 M , 2 M , 3 M ( 3 M is the magnetization for one of the AF sublattices in atomic contact with FM 2 ) and the thicknesses are 1 t , 2 t and 3 t respectively. The free layer is separated from the reference layer by a nonmagnetic metallic spacer of thickness d . The magnetic free energy per unit area of the entire structure can be written as:where the first term represents the free energy of the uncoupled ferromagnetic films:

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Studies of coupled metallic magnetic thin-film trilayers

Cited by 113 publications

References 32 publications

Dynamic effects on the spin-wave spectrum of the bcc thin film

Dynamic effects on the spin-wave spectrum of the bcc thin film

Intensity of Brillouin light scattering from spin waves in magnetic multilayers with noncollinear spin configurations: Theory and experiment

Ferromagnetic resonance dispersion relation of spin valve systems

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