Frequency dependence of the parallel and perpendicular ferromagnetic resonance linewidth in Permalloy films, 2-36 GHz

Patton, Carl E.; Frait, Z.; Wilts, C. H.

doi:10.1063/1.321489

Cited by 63 publications

(27 citation statements)

References 6 publications

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“…2. With the increase of the thickness, G value shows continuous decrease down to the value for thickness of 15 nm which is almost comparable to the bulk value [8]. Similar study has been carried out by S.Mizukami et al [9], their G value for the thin Ta sandwiched NiFe films was nearly independent of the thickness of the NiFe layer.…”

Section: Methodssupporting

confidence: 70%

FMR study on magnetic thin and ultrathin Ni‐Fe films

Zhang

Zhai

et al. 2004

phys. stat. sol. (c)

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Ferromagnetic resonance(FMR) study on sputtered Ni 80 Fe 20 with various thickness from 2 nm to 38.5 nm sandwiched by Ta has been made systematically with different dc magnetic field orientations. The FMR spectra were analyzed and fitted theoretically with Laudau-Lifshitz-Gilbert equation. The variations of magnetization, magnetic anisotropy up to fourth-order term with thickness of samples were obtained. The analysis of the FMR peak-to-peak linewidth was made by the homogenous and inhomogeous contributions, and the damping constants of samples were calculated. The experimental data were fitted by theoretical model and there were some abnormal changes in the magnetic parameters with the sample thickness.

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Section: Methodssupporting

confidence: 70%

FMR study on magnetic thin and ultrathin Ni‐Fe films

Zhang

Zhai

et al. 2004

phys. stat. sol. (c)

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“…The linewidth of the resonance signal for t ¼ 128 Å was % 50 Oe for parallel configuration and % 70 Oe for perpendicular configuration. The resulting from both monolayer and bilayer series fitting values for g=2p are 2.92 GHz/kOe (i.e., g ¼ 2:09) for samples with t ¼ 21 Å and 35 Å , and 2.94 GHz/kOe (i.e., g ¼ 2:10) for the others, the latter value being typical for bulk NiFe [18]. The saturation magnetization was obtained through SQUID measurements of the bilayer samples assuming that the two FM layers have one and the same saturation magnetization.…”

Section: Resultsmentioning

confidence: 99%

Ferromagnetic resonance and magnetization studies in exchange-coupled NiFe/Cu/NiFe structures

Nagamine¹,

Geshev²,

Menegotto³

et al. 2005

Journal of Magnetism and Magnetic Materials

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“…The factor 1͞d does not reflect an intrinsic effect; a reduced total magnetization is simply more sensitive to a given spin-current loss at the interface. Comparing with the intrinsic a 0 ഠ 0.006 of permalloy [12,21] the spin-current induced damping becomes important for ferromagnetic layers with thickness d , 100 Å. We can refine the estimate by including the significant film-thickness dependence of the magnetization measured by the same group [12].…”

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confidence: 99%

Enhanced Gilbert Damping in Thin Ferromagnetic Films

2002

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The precession of the magnetization of a ferromagnet is shown to transfer spins into adjacent normal metal layers. This "pumping" of spins slows down the precession corresponding to an enhanced Gilbert damping constant in the Landau-Lifshitz equation. The damping is expressed in terms of the scattering matrix of the ferromagnetic layer, which is accessible to model and first-principles calculations. Our estimates for permalloy thin films explain the trends observed in recent experiments. DOI: 10.1103/PhysRevLett.88.117601 PACS numbers: 76.50. +g, 72.25.Mk, 73.40. -c, 75.75. +a The magnetization dynamics of a bulk ferromagnet is well described by the phenomenological Landau-Lifshitz-where m is the magnetization direction, g is the gyromagnetic ratio, and H eff is the effective magnetic field including the external, demagnetization, and crystal anisotropy fields. The second term on the right-hand side of Eq. (1) was first introduced by Gilbert [1] and the dimensionless coefficient a is called the Gilbert damping constant. For a constant H eff and a 0, m precesses around the field vector with frequency v gH eff . When damping is switched on a . 0, the precession spirals down to a time independent magnetization along the field direction on a time scale of 1͞av. The study of a in bulk metallic ferromagnets has drawn significant interest over several decades. Notwithstanding the large body of both experimental [2] and theoretical [3] work, the damping mechanism in bulk ferromagnets is not yet fully understood.The magnetization dynamics in thin magnetic films and microstructures is technologically relevant for, e.g., magnetic recording applications at high bit densities. Recent interest by the basic physics community in this topic is motivated by the spin-current induced magnetization switching in layered structures [4 -6]. The Gilbert damping constant was found to be 0.04 , a , 0.22 for Cu-Co and Pt-Co [5,7], which is considerably larger than the bulk value a 0 ഠ 0.005 in Co [6,8]. Previous attempts to explain the additional damping in magnetic multilayer systems involved an enhanced electron-magnon scattering near the interface [9] and other mechanisms [10], both in equilibrium and in the presence of a spin-polarized current.In this Letter we propose a novel mechanism for the Gilbert damping in normal-metal-ferromagnet ͑N-F͒ hybrids. According to Eq. (1), the precession of the magnetization direction m is caused by the torque~m 3 H eff . This is physically equivalent to a volume injection of what we call a "spin current." The damping occurs when the spin current is allowed to leak into a normal metal in contact with the ferromagnet. Our mechanism is thus the inverse of the spin-current induced magnetization switching: A spin current can exert a finite torque on the ferromagnetic order parameter, and, vice versa, a moving magnetization vector loses torque by emitting a spin current. In other words, the magnetization precession acts as a spin pump which transfers angular momentum from the ferromagnet into the norma...

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Frequency dependence of the parallel and perpendicular ferromagnetic resonance linewidth in Permalloy films, 2-36 GHz

Cited by 63 publications

References 6 publications

FMR study on magnetic thin and ultrathin Ni‐Fe films

FMR study on magnetic thin and ultrathin Ni‐Fe films

Ferromagnetic resonance and magnetization studies in exchange-coupled NiFe/Cu/NiFe structures

Enhanced Gilbert Damping in Thin Ferromagnetic Films

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