Showing papers by "Songyou Wang published in 2000"
TL;DR: In this paper, a new type of incidence-angle-variable infrared spectroscopicellipsometer working in the 2100-10'000 wave number range has been designed and constructed.
Abstract: A new type of incidence-angle-variable infrared spectroscopicellipsometer working in the 2100–10 000 wave number range has been designed and constructed. For the system, the analyzer and polarizer were driven by two microstepping motors having hollow shafts and rotating synchronously with a speed ratio of 2:1, i.e., A=2P. The incidence angle can be varied from 30° to 90° with an accuracy of 0.01°. The doubled Fourier transforms as both functions of the wave number and the azimuthal angles of the polarizer and analyzer were carried out and integrated in the system. Two sets of ellipsometric parameters measured in the experiment have been used to test the data self-consistency of the system. In data reduction, the error arising from the slight anisotropy of the stray light was corrected. In application, the complex dielectric function of the Au film was measured with a data accuracy better that 1% in the entire spectral range.
23 citations
TL;DR: In this article, the effect of Fe doped into Pt spacer layers on magnetic and magneto-optical properties for sputtered Pt-Co multilayers (MLs) has been investigated.
Abstract: The effect of Fe doped into Pt spacer layers on magnetic and magneto-optical properties for sputtered Pt-Co multilayers (MLs) has been investigated. It is found that the saturation magnetization M-s fluctuates as a function of Fe doping content x in Pt1-xFex-Co MLs. Also, the polar Kerr rotation theta(k) fluctuates as a function of the Fe doping content in Pt spacer layers. An obvious enhancement of theta(k) can be seen at short wavelength, which is very important to the magneto-optical record at short wavelength. It is assumed that the fluctuation of the saturation magnetization and polar Kerr rotation is due to the change of spin-polarization in PtFe spacer layers as a function of Fe doping content. (C) 2000 Published by Elsevier Science S.A. All rights reserved.
2 citations
TL;DR: In this article, the optical properties of the metal-insulator granular films were studied and the complex dielectric function was measured in the 1.5-4.8-eV photon energy range.
Abstract: To study the optical properties of the metal–insulator granular films, a series of Ni x (SiO 2 ) 1− x and Au x (SiO 2 ) 1− x granular films was made with a variation of x and the annealing process. The complex dielectric function was measured in the 1.5–4.8-eV photon energy range. New spectral features were found in the dielectric functions. For Au x (SiO 2 ) 1− x samples, a new peak in the e 2 spectra is seen around 2 eV, especially for x =0.67. The e 1 spectra change continuously from positive to negative in the low photon energy range, resulting in a true zero of e 1 associated with the plasmon occurring at 2.0–2.5 eV and at about 3.6 eV for the Au- and Ni-based films, respectively. Compared to previous data, the experimental results obtained in this work provide richer information to understand better the optical properties of the metal-granular films that are not well predicted by the theoretical model. The effect will be useful in the metallic multilayer structure design and applications.
2 citations
TL;DR: In this article, the magneto-optical properties of CoxAg100−x granular films annealing at 100, 250, 400, and 500°C were carefully studied.
Abstract: The magneto-optical properties of CoxAg100−x granular films annealing at 100°C, 250°C, 400°C and 500°C, respectively, were carefully studied. Results show that the Kerr rotation and ellipticity increase with increasing of the content of Co. For the sample Co2Ag98, the Kerr effect is enhanced dramatically with the resonant peaks that appeared in the 3.7–4.1 eV photon energy range after annealing. The peaks are attributed to the combined contribution of the plasma oscillation and the new magneto-optical properties of the granular film after annealing. For the sample Co20Ag80, the Kerr effect enhancement at the low-energy peak position is from the contribution of exy, and at the other high-energy peak is mainly attributed to the plasma oscillation. In terms of the diagonal and off-diagonal terms of the dielectric tensor, the line shape of the Kerr spectra is analyzed.
2 citations
TL;DR: For sputtered Co57Mn43/Si film samples with different ferromagnetic thickness, the spectra of the complex magneto-optical polar Kerr rotation and optical constants were ex-situ measured as mentioned in this paper.
Abstract: For sputtered Co57Mn43/Si film samples with different ferromagnetic thickness, the spectra of the complex magneto-optical polar Kerr rotation and optical constants were ex-situ measured. For 5 nm-thick Co57Mn43 film, the Kerr rotation around 4.3 eV was enhanced by a factor of about 10 times with lower loss of the signal intensity as compared to the thick film. Numerical calculations show that the enhancement effect is attributed to an interplay between optical properties of Co57Mn43 and substrate Si that has a strong interband transition (E2) near 4.3 eV.
1 citations
29 Nov 2000
TL;DR: For prepared FexAg100-x granular films, the Kerr rotation and ellipticity change monotonically with the photon energy and after annealing have two peaks near 2.0 and 3.8 eV, respectively as discussed by the authors.
Abstract: For prepared FexAg100-x granular films, the Kerr rotation and ellipticity change monotonically with the photon energy and after annealing have two peaks near 2.0 and 3.8 eV, respectively. The peak value increases with annealing temperature TA. Numerical calculations show that the peak at low energy is induced by the change in the off-diagonal element of dielectric tensor of Fe particles and the peak at high energy results from the changes in optical properties of Ag particles near its plasma absorption edge. These results clearly show the simultaneous existence of both the magneto-optical size effect of Fe particles and optical size effects of Ag particles in metallic granular films.
1 citations
TL;DR: In this article, the authors have made numerical calculations on the MOKE of the IS/MO/IS sandwiches on substrates of single crystal Si, employing a combination of SiN~5Si3N4! and TbFeCo~5Tb27Fe62Co11!.
Abstract: In the NaCl-type cerium, neodymium, and samarium compounds, the Kerr rotation at low temperatures is very large, compared to small values of common magnetic materials, such as Fe, Co, FeCo, and so on. A Kerr rotation of 14° in the infrared range was observed in CeSb compounds at a temperature of 2 K under a large applied field of 5 T. It is puzzling that the reflectivity in the region has a minimum of 25%, instead of zero. Although a 90° Kerr rotation was observed in the same materials, it was argued to be due to a surface state on the peculiar sample, instead of its intrinsic properties. The criteria for the 90° Kerr rotation were studied theoretically that the absorption part of the dielectric tensor is equal to zero, i.e., «xx 9 5«xy 8 50. In addition, the component «xx 8 must be confined between max$u«xy 9 u,12u«xy 9 u% and 1. The simultaneous fulfillment of these requirements imposes several limitations on the elements of the dielectric tensor, and then seriously reduces the number of magnetic compounds that can exhibit the Kerr angle of 90°. In fact, the limitations hold only for single thick homogeneous media. Magnetic layered structures are generally free from these limitations and much easier to obtain 90° Kerr rotation, since in this case reflection from the interfaces is of importance. In this consideration, Uspenskii and Harmon made numerical analysis on magnetic semiconductor/metal structure and found the 90° Kerr rotation in some structures, such as EuS ~EuO, CoCr2S4, and so on!/Ag~Cu and Au!. However, above single-crystalline homogeneous materials or layered structures are hard to make and do not have prerequisite for magneto-optical ~MO! storage materials. So it is simple to wonder whether there is any practical MO structure to realize large Kerr rotation in the visible range. The magneto-optical Kerr effect ~MOKE! has been studied in more general MO/ insulator ~IS! multilayers and layered structures, such as Fe/ alumina ~amorphous!, TbFe/SiO, and so on. For example, a Kerr rotation of as large as 20° was attained in Fe/alumina ~amorphous!. The MOKE enhancement is attributed to the optical interference. Although the sandwich structure of IS/ MO/IS was commonly used, up to date, no one has figured out the huge Kerr rotation of 90°. In this work we have made numerical calculations on the MOKE of the IS/MO/IS sandwiches on substrates of single crystal Si, employing a combination of SiN~5Si3N4! and TbFeCo~5Tb27Fe62Co11!. In
1 citations
TL;DR: In this article, the effect of the Ni addition on the structural, magnetic and magneto-optical properties of CoPt 3 alloy films was investigated with high angle X-ray diffraction results.
1 citations
29 Nov 2000
TL;DR: In this article, a series of Co x Ag 100-x granular films were prepared by ion beam sputtering and annealed at 100 degree(s)C, 250 degree (s), 400 degree, 500 degree, and 1000 degree (S) C, respectively.
Abstract: A series of Co x Ag 100-x granular films was prepared by ion beam sputtering and annealed at 100 degree(s)C, 250 degree(s)C, 400 degree(s)C, 500 degree(s)C, respectively. The optical constants, the complex dielectric function and magneto- optical Kerr parameters were measured at room temperature. It was found that Kerr rotation and ellipticity with increasing of the Co content. For the samples Co 17 Ag 83 , the strong Kerr effect enhancement is observed around the Ag plasma edge. With the annealing temperature increasing, the enhancement peak shifted toward the low photon energy region. From the analysis of the numerical calculations, it is concluded that the magneto-optical Kerr effect enhancement is due to the presence of the steep plasma edge.