First-principles calculations and Bader analysis of oxygen-deficient induced magnetism in cubic BaTiO_3−x and SrTiO_3−x

ABSTRACT

The possibility of oxygen deficient induced magnetism in cubic BaTiO₃ (BTO) and SrTiO₃ (STO) perovskites is investigated by first-principles calculations, using the projector-augmented-wave method, within the generalised gradient approximation (GGA) and generalised gradient approximation with on-site effect (GGA + U), for the exchange correlation potential. For non-stoichiometric BaTiO_3−x and SrTiO_3−x, supercells were created in order to have two vacancy concentrations, i.e. x = 0.125, 0.083. Spin charge distributions and magnetic moments associated with each ion, including local density of states projected in Bader atoms, were analysed by performing a full Bader charge analysis. Results show that oxygen vacancies could induce magnetism in BaTiO_3−x with x = 0.125 and x = 0.083 under GGA and GGA + U approximations. For SrTiO_3−x with x = 0.125, ferromagnetism is induced with GGA, whereas with GGA + U the non-magnetic state is retained. On the other hand, with x = 0.083, ferromagnetism is induced under GGA and GGA + U.

KEYWORDS:

• Ceramics
• density-functional theory
• electronic structure
• first-principles calculations
• perovskites: vacancies

Acknowledgements

Technical support of Rodrigo Domínguez García, administrator of the computer cluster, is greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.