Electronic structure and magneto-optical properties of Co2MnX alloys where X = Ge, Sn and Pb: a First-principles investigation in the LDA plus U approach

We report our ab - initio calculational results for the electronic structures and the magnetooptical (MO) properties of the ferromagnetic Co2MnX full Heusler alloys where X = Ge, Sn and Pb. Employing the +U corrections for the 3d bands of transition-metal atoms in addition to the conventional local density approximation (LDA), we investigate the correlation effect on the MO spectra in a polar geometry and the detailed electronic structures. Results show that the correlation effect results in a blue-shift of the peak positions and a large enhancement of the MO spectra up to double in magnitude compared to the LDA results. We find that our results can be attributed to the increased t (2g) - e (g) splitting of the spin-minority d-bands of both Co and Mn atoms, which indicates a suppression of the diagonal elements of the optical conductivity in the energy region of 1-2 eV where the interband transitions are forbidden.