Vacancy-driven magnetism in nonmagnetic double perovskite Sr2AlNbO6: A first-principles study

• Both Al and Nb vacancies could induce ferromagnetism in Sr2AlNbO6Sr2AlNbO6.
• Ferromagnetism driven by Al vacancy originates from the 2px state of nearest O atoms.
• Ferromagnetism induced by Nb vacancy comes from 2py and 2pz states of nearest O atoms.
• Sr2AlNbO6Sr2AlNbO6 with O vacancy is energetically more favorable than with others.

Based on first-principles calculation the change of structural, energetic, magnetic and electronic properties of double perovskite oxide Sr2AlNbO6 is investigated by introducing intrinsic vacancies. Calculated results show that although both Al and Nb vacancies could induce ferromagnetism the nature of induced ferromagnetism is different. Ferromagnetism driven by Al vacancies originates from the remarkably spin-polarized 2px state of nearest O atoms, whereas that induced by Nb vacancy mainly comes from the partially filled spin-polarized 2py and 2pz states of nearest O atoms. Sr2AlNbO6 with O vacancy is nonmagnetic but energetically more favorable than that with the other three vacancies.