Comparative study of optical and magneto-optical properties ofGdFe2 and GdCo2

Abstract

We report calculations of the optical and magneto-optical properties ofGdFe2 and GdCo2 using the full-potential linear-augmented-plane-wave method. Calculationswith the Coulomb corrected local spin density approximation(LSDA+U) give a better representation of the band structure, density of states andmagnetic moments compared to LSDA alone. However, both LSDA andLSDA+U approximations give fairly good agreement with experimentfor the diagonal optical conductivity. The calculated results forGdCo2 are in better agreement with the ‘oxide corrected’ data. Our results suggest that the data forGdFe2 are most likely influenced by surface oxidation, due to the high reactivity of these compounds. Forthe much smaller off-diagonal components and Kerr rotation, LSDA results are better than theLSDA+U results, particularly in the energy range 0–3 eV. We show that the unphysical negativeellipticity values are taken care of by the use of stronger relaxation, which also improvesthe qualitative agreement with experimental data. Overall we have obtained a fairagreement with the experimental data for both optical and magneto-optical properties. Wefeel that measurements over a larger energy range are required for facilitating an exhaustiveand decisive comparison and also to strengthen the bond between theory and experiments.