Modified effective-medium theory for magneto-optical spectra of magnetic materials

We have modified the Bruggeman effective-medium theory (EMT) to study the microstructural dependence of the magneto-optical spectra in magnetic materials having the off-diagonal elements of the dielectric tensor. To verify the modified theory, optically thick (4-Å Co/9-Å Pt${)}_{77}$ multilayers were prepared at various Ar sputtering gas pressures of 2, 10, and 30 mTorr. The modified effective-medium theory was confirmed to match well with the experimental values of the dielectric tensors of Co/Pt multilayers. We have also applied this modified EMT to a 20-Å-thick Co film having island structure and observed that this modified EMT exhibited a better match to the experimental data than any other existing theories.