Modeling magneto-optic and ellipsometric parameters in magnetic nanoscale multilayers
Multilayers have become an important class of nanostructured materials. Multilayered nanofilms consisting of transition metals, semiconductors and dielectrics have attracted a lot of interest because of their advanced applications in electronics as memory cells, logic gates in magnetic random access memories or read heads in hard disk drives. In all these applications, a precise control of layer thickness, and good interface quality in terms of sharpness and smoothness of the interface, play a crucial role in determining the quality of the final device. In the case of magnetic multilayers, spectroscopic ellipsometry and magneto-optical investigations could be used simultaneously for characterization during the film growth or after film deposition which is equally important [12-14].
Spectroscopic ellipsometry is routinely used to measure thickness and refractive index of transparent thin films. Absorbing films are more difficult to characterize because the optical constants (n and k) are often correlated with the film thickness. In the case of magnetic films, it is of interest to employ magnetic methods to get information on magnetic parameters and as an additional tool for structure characterisation. In this paper, a combined model for ellipsometry and magneto-optic Kerr effect (MOKE) investigations has been developed. The phenomenological description of optical and magneto-optical parameters is based on the matrix form of the permittivity. In the case of equatorial MOKE the p- and s- polarized waves remain the eigenfunctions and the consideration is convenient to make in terms of Abeles matrices. Using data for thin films of Co and Fe, we have investigated the method sensitivity demonstrating that the change in the ellipsometry parameters due to magnetic layer remagnetization is in the range of 0.1 degrees which is larger than the ellipsomer resolution. This suggests that the both methods could be successfully integrated.
Scientific adviser - Ph. D. Panina Larissa Vladimirovna