DIELECTRIC TENSOR CHARACTERIZATION AND EVALUATION OF SEVERAL MAGNETOOPTICAL RECORDING MEDIA

We attempt to establish a dielectric tenser database for magneto-optical (MO) thin film materials with potential application for blue recording. For this purpose a method is developed for measuring the dielectric tenser of the MO layer within a multilayered stack. It uses a combination of ellipsometric, reflection/transmission, and polar MO Kerr effect measurements, and employs the MULTILAYER computer program to analyze the data. Using this approach we have measured the dielectric tenser for thin films of BiDy3(FeGa)(5)O-12 garnet, MnBi multilayered Co/Pt, amorphous TbFeCoTa, and fee cobalt in the wavelength range of 400-780 nm. The dielectric tenser for the Heusler alloy films of PtMnSb, which is available from the published literature, is also presented for the sake of completeness. These materials are then evaluated based on the intrinsic MO figure of merit defined by FOM = \epsilon(xy)\/(2 Im epsilon(xx)), where epsilon(xx) and epsilon(xy) are the diagonal and off-diagonal elements of the dielectric tenser of the MO material. In the blue-green regime of 400-550 nm, the relationship of the derived FOMs is as follows: FOM(MnBi)(approximate to 0.027-0.045) approximate to FOM(Garnet) (approximate to 0.023-0.032) > FOM(PtMnSb)(approximate to 0.015-0.026) > FOM(Co/Pt)(approximate to 0.013-0.015) approximate to FOM(Co(fcc)) (approximate to 0.011-0.016)> FOM(TbFeCoTa) (approximate to 0.009-0.011). (C) 1995 American Institute of Physics.