Spin-polarised band structure for the semimagnetic semiconductor Zn_0.5Mn_0.5Se

The spin-polarised band structure, density of states (DOS), magnetic moments and exchange interaction coefficients for a layer structure Zn_0.5Mn_0.5Se in the ferromagnetic phase have been calculated using the self-consistent linear muffin-tin orbital atomic sphere approximation method. Its band structure and DOS distribution are explained through a p-d repulsion model. The band structure in the antiferromagnetic phase is also analysed qualitatively in terms of the p-d repulsion mechanism. The results of the present work show that the bands are strongly polarised. In the case of spin up, the bands are direct, with a band gap of 0.68 eV and a filled Mn 3d valence band whereas, for the spin-down case, the bands are indirect, with a band gap of 1.81 eV and an empty Mn 3d conduction band. These results are in agreement with Hund's rule. The calculated total magnetic moment is 4.81 mu _B/cell; the p-d and s-d exchange interaction coefficients are -1.10 eV and 0.04 eV, respectively.