Electronic Structure and Half-Metallic Character in Sr2CoB′O6 (B′ = Mo, Re) Materials

We report several ab initio calculations performed for Sr2CoB'O-6 (B' = Mo, Re) by means of the Density Functional Theory and the Linearized Augmented Plane Waves method with spin polarization. For the calculations, the exchange and correlation potentials were included through the local density LDA+U approximation with B3PW91. Density of states (DOS) study was carried out considering both up and down spin polarizations by the Generalized Gradient Approximation (GGA). From the Murnaghan state equation, we calculate the cell dimensions that minimize the total energy. Our results of DOS calculations show that the Sr2CoMoO6 material presents a metallic behavior, while Sr2CoReO6 reveals a half-metallic nature with conductor behavior for the spin down orientation and semiconducting feature for spin up channel. It was observed close to Fermi level that the low-energy spin down states of Co are responsible by the majority contribution to conduction band. The calculated effective cell magnetic moment of the Sr2CoReO6 compound evidences a value 2.02 mu(B), which is close to an integer number as expected for a half-metallic material.