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31.
Ping Chen Min LiuLing Wang Yin PooRui-xin Wu 《Journal of magnetism and magnetic materials》2011,323(23):3081-3086
We experimentally studied the frequency dependent complex permittivity ε and permeability μ of composite composed of carbonyl iron powder (CIP) and epoxy resin in the frequency range 1-18 GHz. We found that the intrinsic ε and μ of CIP extracted from the measured ε and μ of composites follow the classical Maxwell equations and the Landau-Lifshitz-Gilbert (LLG) equation, respectively. The dependences of ε and μ of composites on the volume fraction of CIP (vfCIP) were investigated using the two-exponent phenomenological percolation equation (TEPPE). We found that the TEPPE can fit the experimental results very well. Comparing the results of percolation parameters derived by experimental data at different frequencies, we show that the TEPPE is frequency independent for the composites at microwave frequencies. The results also show that the ε and μ spectrums of composites with definite vfCIP can be correctly calculated by combining the TEPPE with the theoretical models of intrinsic ε and μ. 相似文献
32.
L. Wee R. L. Stamps Z. Celinski L. Malkinski D. Skrzypek 《Journal of magnetism and magnetic materials》2002,240(1-3):270-272
Magnetic anisotropies at epitaxial Fe/KNiF3 interfaces were probed by ferromagnetic resonance. Fe(0 0 1) films coupled to single crystal KNiF3 exhibit four-fold in-plane anisotropy and a unidirectional bias upon field-cooling. In Fe(0 0 1) with polycrystalline KNiF3, the bias direction deviates from the field-cooling direction. Lattice mismatch strain due to polycrystalline KNiF3 also induces uniaxial anisotropy in Fe. 相似文献
33.
(0 0 1)Fe-mesa were grown on a GaAs high electron mobility transistor (HEMT)-structure. Magnetic properties were investigated by locally resolved photothermally modulated ferromagnetic resonance (PM-FMR). The surface and the in-plane anisotropy are decreased in HEMT-areas. The field independent response of PM-FMR provides information on the electrical properties of the GaAs-heterostructure and yields evidence of preparation dependent lifetime effects of the photo-carriers. 相似文献
34.
NiO nanoparticles with an average size of 15 nm were easily prepared via the thermal decomposition of the tris(ethylenediamine)Ni(II) nitrate complex [Ni(en)3](NO3)2 as a new precursor at low temperature, and the nanoparticles were characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV-Vis spectroscopy, BET specific surface area measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and magnetic measurements. The magnetic measurements confirm that the product shows a ferromagnetic behavior at room temperature, which may be ascribed to a size confinement effect. The NiO nanoparticles prepared by this method could be an appropriate photocatalytic material due to a strong absorption band at 325 nm. This method is simple, fast, safe, low-cost and also suitable for industrial production of high purity NiO nanoparticles for applied purposes. 相似文献
35.
A new linear trinuclear nickel(II) complex, [Ni3L2(OCn)4] (HL = 2-[(3-dimethylamino-propylimino)-methyl]-phenol, OCn = cinnamate), with phenoxo bridge and a novel tridentate bridging mode (in a 2.21 fashion according to Harris notation), of the cinnamate ligand has been synthesized and characterized by IR spectroscopy, UV-Vis spectroscopy, X-ray crystallography and static magnetic measurements. The molecular structure shows that each nickel ion occupies octahedral coordinating geometry. Apart from the phenoxo bridges, the carboxylic group of cinnamic anion shows two types of bridging modes viz. 2.11 and 2.21. The magnetic data indicate that a moderate intramolecular ferromagnetic and a weak intermolecular antiferromagnetic interaction are present in the complex under study. Broken symmetry density functional theory has been used to estimate the sign and magnitude of the coupling constants to understand the magnetic exchange mechanisms of the present system. The relative abilities of different bridging groups to mediate magnetic exchange interactions between paramagnetic nickel centers have been investigated by DFT calculation with variable angles. The results show that a small change in phenoxo-bridging angle has a very strong impact on the magnetic properties. 相似文献
36.
Lattice dynamics and electron-phonon coupling are calculated for non-magnetic hcp iron at 100 GPa by a first-principles linear response full-potential LMTO method. Superconducting transition temperature is estimated to be less than 0.5 K. For ferromagnetic bcc iron lattice dynamical calculations are performed for 9.8 GPa as well as for ambient pressure. The results of calculation reproduce well the pressure dependence of phonon dispersion curves observed by neutron scattering measurements. 相似文献
37.
The magnetic properties of Fe/Zn/Fe trilayers have been studied by ferromagnetic resonance and magnetization measurements. These measurements have been used to investigate the magnetic anisotropy of the iron layers and the magnetic coupling across the semiconductor spacer. The angular dependence of the resonance spectra has been measured in-plane and out-of-plane in order to deduce magnetic anisotropy constants of the samples. Experimental data were fitted by using an energy-density expression that includes bulk cubic anisotropy, growth-induced uniaxial in-plane anisotropy and perpendicular-surface anisotropy terms. A small ferromagnetic coupling is observed in the trilayers with spacer thickness up to
. 相似文献
38.
A. M. Zabolotskiy D. P. Belozorov S. I. Tarapov 《International Journal of Infrared and Millimeter Waves》2004,25(10):1431-1438
The numerical simulation of the Ferromagnetic Resonance (FMR) absorption in the millimeter waveband has been performed for magnetic multilayered nanostructures. The model taking into account a random bilinear exchange interaction between layers was applied for the theoretical approach elaboration. Results of the simulation are in good agreement with experimental data registered for samples of nanostructure Co/Cu with buffer layer Fe in the frequency band 20-37 GHz. The explanation of the origin of unexpectedly broad magnetoresonance peaks formed in specimen under study is suggested. 相似文献
39.
LaBaMnO薄膜的铁磁共振 总被引:1,自引:1,他引:0
用电子自旋共振实验研究La0.65Ba0.35MnO3(LBMO)薄膜的磁性,从磁性膜的各向异性铁磁共振谱得到不同角度θh时的共振磁场Br,求出样品的等效磁场Beff及旅磁比γ,并通过样品的饱和磁化强度Ms,求出各向异性常数K. 相似文献
40.
P. Evans C. Scheck R. Schad G. Zangari 《Journal of magnetism and magnetic materials》2003,260(3):467-472
The structural and magnetic properties of Ni films grown by electrodeposition from simple sulfate solutions directly onto the (0 0 1) and (0 1 1) surfaces of n-GaAs have been studied. In-plane X-ray diffraction has been used to show that Ni grows on (0 0 1) GaAs with two different preferred epitaxial relationships: (1) perpendicular to plane (0 0 1)Ni(0 0 1)GaAs and preferred orientation in-plane [1 0 0]Ni[1 1 0]GaAs and (2) perpendicular to plane (0 1 1)Ni(0 0 1)GaAs and preferred orientation in-plane [1 1 1]Ni[1 1 0]GaAs. Nickel films grown on (0 1 1) n-GaAs show only a single preferred growth relationship: perpendicular to plane (1 1 1)Ni(0 1 1)GaAs and in-plane [1 1 0]Ni[1 1 0]GaAs. The magnetic properties were strongly dependent on the substrate orientation. The films grown on GaAs (0 0 1) showed a small but definite four-fold magnetic anisotropy in plane with the highest remanence being found along the GaAs [1 0 0] direction. In contrast, the Ni films grown on the (0 1 1) GaAs showed a pronounced uniaxial anisotropy with an anisotropy field of approximately 500 Oe. 相似文献