Comparative study of optical and magneto-optical properties and electronic structure of ferrimagnetic GdFe2 and GdCo2

The optical and magneto-optical properties of single-crystalline GdFe2 and GdCo2 were measured by ellipsometry and magneto-optical Kerr effect spectroscopy in the 1.4–5.3 eV range. The optical constants of the compounds are quite similar to each other in the whole energy range. On the other hand, their magneto-optical constants behave differently from each other with the structural peaks for GdCo2 shifted to higher energies by about 0.5 eV from those for GdFe2. The results indicate that magneto-optical measurements can detect differences in the electronic structure between the two compounds while optical measurements cannot. The peak shift is interpreted as due to a stronger d hybridization in GdCo2 than in GdFe2, leading to larger d-state binding energies for GdCo2 than those for GdFe2.