Ab Initio study of half-metallic feature and electronic structure of A 2FeMoO6 (A=Ba,Ca) magnetic system

Abstract

We report several ab initio calculations performed over the A 2FeMoO6 (A=Ba, Ca) double perovskite. Results show that it is an insulator for the spin up orientation and conductor for the other one. We investigate the electronic structure of A2FeMoO6 by means calculations of density of states for both spin orientations, based on the Density Functional Theory and the Linearized Augmented Plane Waves method. For the exchange correlation potential we chose the Generalized Gradient Approximation since this potential consider the difference between the electronic densities for the two distinct spin orientations from the beginning. The density of states is calculated by the histogram method and the position of the Fermi level is found by integrating over the density of states for both spin orientations. With the calculated densities of states, the half metallic properties of these compounds can be observed with the position of the Fermi level. Our results are in agreement of the Sarma's methodology, who considers a new mechanism for the magnetic interactions responsible for the magnetism on the A2FeMoO6 family. We also calculate the cell dimensions that minimize the total energy for each configuration using the Murnaghan equation state.