Electronic structure and magneto-optical properties of magnetic semiconductors: Europium monochalcogenides

Electronic structure and magnetic properties of Europium monochalcogenides (EuX, X=O, S, Se, and Te) have been investigated by the full potential linear muffin-tin orbital method. The generalized gradient approximation (GGA) including on site Coulomb interaction of 5d and 4f states (GGA+U₃+U₅) has been used to describe the complicated properties of EuX. The GGA+U₅ band structure underestimates the band gap. GGA+U₃+U₅ gives better agreement in terms of band gap and the positions of 4f bands of EuX. GGA+U₃+U₅ gives much improved Kerr spectra for all the EuX over the standard LSDA and GGA+U₅ spectra although the magnitude of the first peak is less satisfactory in the dielectric function spectra. The Coulomb correlation effects among 4f and 5d electrons of Eu play important role to determine the optical spectra of EuX.