First-principles study of strain effect on the formation and electronic structures of oxygen vacancy in SrFeO ₂

Abstract

Motivated by recent experimental observations of metallic conduction in the quasi-two-dimensional SrFeO 2 , we study the epitaxial strain effect on the formation and electronic structures of oxygen vacancy (V o ) by first-principles calculations. The bulk SrFeO 2 is found to have the G-type antiferromagnetic ordering (G-AFM) at zero strain, which agrees with the experiment. Under compressive strain the bulk SrFeO 2 keeps the G-AFM and has the trend of Mott insulator-metal transition. Different from most of the previous similar work about the strain effect on V o , both the tensile strain and the compressive strain enhance the V o formation. It is found that the competitions between the band energies and the electrostatic interactions are the dominant mechanisms in determining the V o formation. We confirm that the V o in SrFeO 2 would induce the n-type conductivity where the donor levels are occupied by the delocalized d x 2 −y 2 electrons. It is suggested that the vanishing of n-type conductivity observed by the Hall measurement on the strained films are caused by the shift of donor levels into the conduction band. These results would provide insightful information for the realization of metallic conduction in SrFeO 2 .

Magnetocrystalline anisotropy and dynamic spin reorientation of half-doped Nd0.5Pr0.5FeO3 single crystal*

“…The increasing magnetization at ∼ 17 K may be linked to the transition from low-spin (S = 1/2) to high-spin (S = 5/2) state of Fe 3+ . [22,23] The volume change of Fe 3+ gives rise to the conflict of atomic Hund rules due to the changed crystal field and results in a further enhancement of the total moment (see the insets of Fig. 3).…”

Study of magnetic and optical properties of Zn 1− x TM x Te ( TM = Mn, Fe, Co, Ni) diluted magnetic semiconductors: First principle approach

“…A wide range of theoretical and experimental reports, available in the literature, depict huge motivations to explore interesting materials for versatile device functionalities. [1][2][3][4][5][6][7][8][9][10] The semiconductors belonging to II-VI, III-VI, IV-VI, are extensively being explored for various applications. Particularly, the II-VI based DMSs, for example ZnS, ZnSe, and ZnTe, are considered to be attractive owing to their wide direct band gaps, which can offer versatile opto-electronic characteristics, therefore, could be expected to replace the existing siliconbased devices.…”