First-principles investigation of magnetic coupling mechanism in A-site-ordered perovskite CaFe3Ti4O12

We have investigated the electronic and magnetic properties of A-site-ordered perovskite CaFe3Ti4O12 using first-principles calculations. Our calculated results indicate that CaFe3Ti4O12 is mechanically stable and it is an antiferromagnetic insulator. Similar to its isostructural perovskite CaCu3Ti4O12, the primary magnetic coupling mechanism in CaFe3Ti4O12 is ascribed to the Fe–O–Ti–O–Fe superexchange interaction. From this fact we can clearly see that the empty 3d orbitals play an important role to realize the superexchange interaction. Moreover, comparing CaFe3Ti4O12 and CaCu3Ti4O12 in some details, we find that Fe (Cu)–O bond distance is one of the important parameters to determine the antiferromagnetic strength within this superexchange interaction.