Unraveling the structural stability and UV optical response of Mn-doped Sr2LaSbO6 via DFT investigations

Abstract

Sr₂LaSbO₆ is a double perovskite of the A₂BB′O₆ type, comprising SbO₆ octahedra, and exhibits promising luminescent properties when activated by Mn4⁺ ions. First-principles Density Functional Theory (DFT) calculations were performed to investigate the structural, electronic, magnetic, and optical properties of Mn-doped SLSO. Structural stability was confirmed through the Birch–Murnaghan equation of state by determining the ground-state energy. Due to electron transfer, the moderate ionic bonding between La/Sb and the more electronegative O atoms contributes to the structural stability of the compound. Mn-doped Sr₂LaSbO₆ exhibits metallic behaviour in the spin-up channel with states crossing the Fermi level, while the spin-down channel remains semiconducting, confirming its half-metallic character. Manganese (Mn) ions exhibit a high positive magnetic moment, contributing significantly to the overall ferromagnetic behaviour of the compound. The small positive magnetic moment observed on oxygen (O) atoms is likely due to spin polarization induced by interactions with neighbouring magnetic Mn ions. Optical property calculations indicate that the material exhibits a strong optical response, primarily in the ultraviolet region. This research established that Mn-doped Sr₂LaSbO₆ demonstrates structural stability, half-metallic ferromagnetism, and a strong ultraviolet optical response, making it a promising candidate for spintronic and optoelectronic applications.