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Magneto -optic and dielectric properties of MO materials
Magneto-optic materials have attracted large interests for more than two decades, and magneto-optic disks made from rare-earth transition metal alloy films have been commercially available since the late 1980's. Transition metal/ferromagnetic multilayer structures were developed in the late 1980's and are considered future magneto-optic media for blue lasers. However, even though theoretical calculations for dielectric tensors have been performed to study the physical origins of magneto-optical phenomena in the multilayer structures, very little work has been done to study the dielectric properties of individual layers. ^ In this dissertation, comprehensive dielectric property studies are performed for magnetic multilayer structures, including magnetron sputter deposited Pt/Co, Au/Co, Pd/Co/, Cu/Co, and Pt/Fe. The full dielectric tensor for magnetic layers and interfacial layers in these structures were determined. The most extensive work was done for Pt/Co structures. Also, the full dielectric tensor for the Heusler compound material NiMnSb was determined, and further studied using a phenomenological Lorentz oscillator model. The results were compared to previously published theoretical predictions, and origins of the Kerr response for these materials were discussed. ^ Two steps were needed to determine the full dielectric tensor. First, the uniaxial dielectric functions (diagonal parts of the dielectric tensors) were determined by in situ spectroscopic ellipsometry and ex situ spectroscopic ellipsometry, for the magnetic multilayer structures and for the NiMnSb thin film structures. Second, the off-diagonal part of the dielectric tensors for all materials were determined by ex situ spectroscopic magneto-optic analysis. ^ As well as the individual layer optical constants, the individual layer thicknesses on a nanometer scale are very important parameters for magneto-optic studies of multilayer structures. In the work of this dissertation, techniques using in situ spectroscopic ellipsometry have been developed to determine these two parameters simultaneously. ^ Reviews of the experimental and theoretical development of magneto-optic multilayer structures and in situ spectroscopic ellipsometry are given in this dissertation. The theoretical basics of ellipsometry, regression analysis, and magneto-optic analysis of dielectric tensors are also reviewed. ^ The experimental results and analysis are summarized in Chapter 3. The detailed experimental results and analysis are presented as Appendices, using the associated referenced articles published during the period of this dissertation work. ^
Engineering, Electronics and Electrical|Engineering, Materials Science
Gao, Xiang, "Magneto -optic and dielectric properties of MO materials" (2000). ETD collection for University of Nebraska - Lincoln. AAI9976991.