Magneto-optical Kerr effect of amorphous TbFeCoTa film with a quadrilayer structure

The magneto-optical Kerr effect (MOKE) of a multilayered system has been described by using the characteristic matrix method of film optics. By using this method, the MOKE and read-out performance of an amorphous TbFeCoTa film with the quadrilayer structure of SiC/TbFeCoTa/SiC/metallic reflector/glass substrate, has been investigated in detail. Different from the MO/metallic bilayer structure, whose Kerr rotation can be strongly enhanced by the metallic reflector with low values of the optical constants n and kappa, the Kerr rotation and the read-out figure of merit of the quadrilayer structure are strongly enhanced at wavelengths where the reflector layer has a high reflectivity, due to multiple reflection and optical interference. Among the Al, Ag, Cu, Cr and Au reflectors, Al and Ag reflectors result in the largest two increments in the Kerr rotation and the read-out figure of merit at short wavelengths, indicating that Al and Ag are the best reflector materials for the TbFeCoTa MO disk for short wavelength recording. The thickness dependencies of each layer on the MOKE, reflectivity and the figure of merit of the quadrilayer structure have been investigated. By employing this method, the optimum structure for the TbFeCoTa MO disk can be determined.