Abstract
Nanocrystalline Co40Fe40B20 films, with film thickness tf = 100 nm, were deposited on glass substrates by the magnetron sputtering method at room temperature. During the film deposition period, a dc magnetic field, h = 40 Oe, was applied to introduce an easy axis for each film sample: one with h||L and the other with h||w, where L and w are the length and width of the film. Ferromagnetic resonance (FMR), ultrahigh frequency impedance (IM), dc electrical resistivity (ρ), and magnetic hysteresis loops (MHL) of these films were studied. From the MHL and r measurements, we obtain saturation magnetization 4πMs = 15.5 kG, anisotropy field Hk = 0.031 kG, and r = 168 mW.cm. From FMR, we can determine the Kittel mode ferromagnetic resonance (FMR-K) frequency fFMRK = 1,963 MHz. In the h||L case, IM spectra show the quasi-Kittel-mode ferromagnetic resonance (QFMR-K) at f0 and the Walker-mode ferromagnetic resonance (FMR-W) at fn, where n = 1, 2, 3, and 4. In the h||w case, IM spectra show QFMR-K at F0 and FMR-W at Fn. We find that f0 and F0 are shifted from fFMRK, respectively, and fn = Fn. The in-plane spin-wave resonances are responsible for those relative shifts.PACS No. 76.50.+q; 84.37.+q; 75.70.-i
Highlights
It is known that impedance (IM) of an ferromagnetic (FM) material is closely related to its complex permeability (μ ≡ μR + i μI ), where μR and μI are the real and imaginary parts, in the high-frequency (f) range [1,2]
The thickness dependence is due to the eddy current effect, while the upper limit is due to the spin relaxation effect
With regard to the Ferromagnetic resonance (FMR)-K mechanism, we propose the following model: When ferromagnetic resonance of the Kittel mode (FMR-K) occurs in Figure 2, we have [9]
Summary
It is known that impedance (IM) of an ferromagnetic (FM) material is closely related to its complex permeability (μ ≡ μR + i μI ), where μR and μI are the real and imaginary parts, in the high-frequency (f) range [1,2]. The result is shown, where we can spot an FMR (or FMR-K) event at H = HR = 0.68 kG, and define the half-peak width ΔH = 53 Oe. Other magnetic and electrical properties of the Co40Fe40B20 film were obtained from vibration sample magnetometer measurements: 4πMs = 15.5 kG and the anisotropy field, Hk = 0.031 kG, and from electrical resistivity (r) measurement: r = 168 μΩ.
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