Interfaces of Fe/Si multilayered films with a strong antiferromagnetic coupling analyzed by optical and magneto-optical spectroscopies

Fe/Si multilayered films (MLF) exhibiting a strong antiferromagnetic (AF) c oupling were investigated by optical and magneto-optical (MO) spectroscopie s. The results were compared with the computer-simulated spectra based on v arious structural models of MLF. It was shown that neither semiconducting F eSi2 nor epsilon -FeSi can be considered as the spacer layers in the Fe/Si MLF for the strong AF coupling. The optical properties of the spacer extrac ted from the effective optical response of the MLF strongly support its met allic nature. A reasonable agreement between experimental and simulated equ atorial-Kerr-effect spectra was obtained with the fitted optical parameters of the spacer with the FeSi stoichiometry. Comparison of the extracted opt ical properties of the spacer with the calculated ones by using the first p rinciples showed that a B2-phase metallic FeSi compound is spontaneously fo rmed at the interfaces during deposition. For the Fe/Si system with ultrath in Fe and Si sublayers (thinner than 1 nm), our optical data indicate that the structure of the whole MLF is close to the amorphous and semiconducting epsilon -FeSi. (C) 2001 American Institute of Physics.