Structural, electronic and magnetic properties of stoichiometric, La- and O-deficient bulk L a 0 . 75 C a 0 . 25 M n O 3 compounds have been studied within the spin polarized GGA+U approximation of density functional theory. La-deficient L a 0 . 75 C a 0 . 25 M n O 3 exhibits an insulating G-type antiferromagnetic nature, and shows an energy gap of 0.655 eV. The O-vacancy L a 0 . 75 C a 0 . 25 M n O 2 . 75 and L a 0 . 75 C a 0 . 25 M n O 2 . 50 compounds show a ferromagnetic and A-type antiferromagnetic metallic behavior, respectively with an increased on-site Mn magnetic moment. Projected density of states show a more occupation of e g orbitals for La 0 . 75 C a 0 . 25 M n O 2 . 75 and La 0 . 75 C a 0 . 25 M n O 2 . 5 , suggesting existence of Mn 2 + along with Mn 3 + and Mn 4 + . e g orbitals are almost fully unoccupied, suggesting the dominant presence of Mn 4 + in L a 0 . 5 C a 0 . 25 M n O 3 compound. These findings provide a useful insight of how increased M n 4 + valence, and the existence of M n 2 + valence in mixed-valence perovskite can manage the orbital ordering for switching ferromagnetism and antiferromagnetism. • Effect of La and O deficiency on orthorhombic ferromagnetic metallic La 0.75 Ca 0.25 MnO 3 properties has been studied using DFT+U method. • La 0.5 Ca 0.25 MnO 3 compound is a G-type antiferromagnetic insulating with higher Mn 4+ content. • La 0.75 Ca 0.25 MnO 2.75 compound is a F-type ferromagnetic metallic, concomitant with the existence of Mn 2+ ions. • Further O-deficiency suppress the ferromagnetic double exchange interaction and favors the antiferromagnetic super exchange interaction. • O-deficiency stabilizes mainly in the La-O1 plane.
Mouketo et al. (Sun,) studied this question.