共查询到20条相似文献,搜索用时 15 毫秒
1.
In order to describe high-frequency damping mechanisms of ferromagnetic films by means of the imaginary part of the frequency-dependant permeability, CMOS compatible ferromagnetic Fe36Co44Hf9N11 films were deposited by reactive r.f. magnetron sputtering on oxidised 5×5 mm2×380 μm (1 0 0)-silicon substrates with a 6-in. Fe38Co47Hf15 target, as well as magnetic field annealing between 300 and 600 °C. An in-plane uniaxial anisotropy of around 4.5 mT as well as an excellent soft magnetic behaviour with a saturation polarisation of approximately 1.4 T could be observed after heat treatment at the above-mentioned temperatures, which drives these films to a high-frequency suitability. Ferromagnetic resonance frequencies of approximately up to 2.4 GHz could be obtained. The frequency-dependant permeability was measured with a broadband permeameter. Depending on the heat treatment, an increase of the full-width at half-maximum (FWHM) of the imaginary part of the frequency-dependant permeability is discussed in terms of two-magnon scattering, anisotropy-type competition and local resonance generation through predominant grain growth causing magnetisation and anisotropy inhomogeneities in the magnetic films. The grain size of the films was determined by (HRTEM) imaging and amounts from a few nanometres for films heat treated at 300 °C to more than 10 nm at 600 °C where the FWHM Δfeff and the Landau–Lifschitz–Gilbert equation damping parameter αeff increases with dnm2 and dnm (e.g. dnm is the grain diameter of the nonmagnetic Hf–N phase), respectively. 相似文献
2.
S. A. Vyzulin E. V. Lebedeva A. V. Maksimochkina N. S. Perov N. E. Syr’ev I. T. Trofimenko 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(5):673-676
The static magnetic properties and ferromagnetic resonance spectra of multilayer CoFeZr-α-Si films with different numbers and thicknesses of magnetic and nonmagnetic layers have been investigated. It is established that the shape of the ferromagnetic resonance spectrum and the resonant fields H res depend on the thickness of nonmagnetic layers and their total number. The character of changes in the spectrum makes it possible to estimate the quality of layers and interfaces. 相似文献
3.
We report temperature and field dependent lattice structure, magnetic properties and magnetocaloric effect in epitaxial Fe50Rh50 thin films with (001) texture. Temperature-dependent XRD measurements reveal an irreversible first-order phase transition with 0.66% lattice change upon heating/cooling. First-principle calculation shows a state change of Rh from non-magnetic (0 μB) for antiferromagnetic phase to magnetic (0.93 μB) state for ferromagnetic phase. A jump of magnetization at temperature of 305 K and field more than 5 T indicates a field-assisted magnetic state change of Ru that contributes to the jump. Giant positive magnetic entropy change was confirmed by isothermal magnetization measurements and an in-situ temperature rise of 15 K. The magnetic state change of Rh between antiferromagnetic and ferromagnetic states is the main origin of giant magnetic entropy change and large thermal hysteresis observed. 相似文献
4.
Frank Hubenthal 《Applied physics. B, Lasers and optics》2014,116(1):1-5
In this contribution, a fundamental new approach is made to explain high enhancement factors in surface-enhanced Raman spectroscopy (SERS) on the basis of chemical enhancement. Usually, high SERS enhancement factors are explained by electromagnetic enhancements due to the excitation of localized surface plasmon resonances and strong near field dipole–dipole coupling. However, very often the corresponding SERS spectra show clear signatures of a chemical enhancement. I propose that this contradiction is easily solved by taking chemical interface damping of the plasmon resonance into account. Chemical interface damping is caused by an electron transfer from the metallic structure into an adsorbate. However, this mechanism is also the basis for chemical enhancement in SERS, i.e., an electron transfers in the lowest unoccupied molecular orbital of the molecule and back to the metal. Hence, if a molecule causes a strong chemical interface damping, the excitation of plasmons is still the key factor for the SERS enhancement. But the reason for this enhancement might be not solely due to electromagnetic fields rather than by a chemical enhancement due to electron transfers from the metal to the molecules. 相似文献
5.
The Fourier transform gas-phase IR spectrum of 1,3,4-thiadiazole, C2H2N2S, has been recorded with a resolution of ca. 0.003 cm−1 in the 800-1500 cm−1 spectral region. Five fundamental bands ν2(A1; 1391.9 cm−1), ν4(A1; 964.4 cm−1), ν5(A1; 894.6 cm−1), ν9(B1; 821.5 cm−1), and ν14(B2; 898.4 cm−1) have been analysed using the Watson model. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. The ν4 and ν9 bands are unperturbed while a strong c-Coriolis resonance perturbs the close-lying ν5 and ν14 bands. This dyad system has been analysed by a model including first and second order c-Coriolis resonance using the theoretically predicted Coriolis coupling constant . The ν2 band is strongly perturbed by a local resonance, and we obtain a set of spectroscopic parameters using a model including second order a-Coriolis resonance with the inactive ν10 + ν14 band. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement. 相似文献
6.
Jean-Pierre Bouanich Jamel Salem Jacques Walrand 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,84(2):195-205
H2-broadening coefficients are measured for 41 transitions of PH3 in the QR branch of the ν2 band and the PP, RP, and PQ branches of the ν4 band, using a tunable diode-laser spectrometer. The recorded lines with J values ranging from 2 to 16 and K from 0 to 11 are located between 995 and . The collisional widths are determined by fitting each spectral line with a Voigt profile, a Rautian profile, and a speed-dependent Rautian profile. The latter model provides larger broadening coefficients than the Voigt model. These coefficients γ0(J,K) are found to decrease slightly on the whole as J increases and they decrease significantly for K values approaching or equal to J(J?4). The H2-broadenings are also calculated on the basis of a semiclassical model of interacting linear molecules, using an atom-atom Lennard-Jones potential in addition to the weak electrostatic contributions. The theoretical results are in satisfactory agreement with the experimental data and reproduce the J and K dependencies of the broadenings, but the decrease observed for the QR(J,K) transitions with K=J is notably overestimated. 相似文献
7.
Kensuke Harada Makoto Hatanaka Akira Inayoshi Keiichi Tanaka Takehiko Tanaka 《Journal of Molecular Spectroscopy》1984,108(2):249-263
The LMDR (laser-microwave double resonance) spectroscopy with an intense electric field was applied to the ν5 (CF3 degenerate stretch) fundamental band of CDF3. The dipole moments and polarizability anisotropies in the ground and ν5 vibrational states were determined as follows.
Ground | ||
μ (D) | 1.653 511 (29) | 1.658 514 (23) |
α (Å3) | ?0.77 (32) | ?0.58 (48) |
20Ne | 22Ne | |
Neenergy (keV) | 239.12±0.14 | 230.49±0.88 |
width (keV) | 15.43±0.41 | 12.65±3.51 |
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