Electronic structure of A2CrSbO6 [A=Sr, Ca]: Ab-initio study

First principles calculations have been performed to study the electronic structure and magnetic properties of Cr-based double perovskite oxides Sr2CrSbO6 and Ca2CrSbO6 using full potential linearized augmented plane wave method under generalized gradient approximation (GGA) scheme. In our calculation, we have applied onsite Coulomb potential U at Cr site. The density of states (DOS) of Sr2CrSbO6 has been studied in three different crystal structures. Due to the different crystal symmetry of Sr2CrSbO6 at different temperatures, the DOS spectra differ from one another near the Fermi level. The insulating ground states have been obtained from GGA+U calculation for both the materials. It has been observed from DOS spectra that oxygen 2p-derived states hybridize strongly with Cr-d states and this hybridization plays an important role in the magnetic properties. The calculated magnetic moments for Cr are found to be 2.65, 2.60 and 2.72 μB for monoclinic, tetragonal, cubic phases of Sr2CrSbO6, respectively and 2.68 μB for Ca2CrSbO6. The obtained magnetic moments suggest the 3+ states of Cr (3d3) in these oxides.

► First principles calculations of electronic structure of Sr2CrSbO6 and Ca2CrSbO6. ► Insulating nature of the materials has been observed from DOS. ► Valence state of Cr ion is t2g3eg0 in Sr2CrSbO6 and Ca2CrSbO6. ► GGA+U increases band gap and magnetic moment for Cr.