Effects of the vacancy and doping on the half-metallicity in La0.5Sr0.5MnO3

• The perfect and defective La0.5Sr0.5MnO3 are found to be half-metallic ferromagnets.
• The gap width decreases according to the order of the perfect, VO and DN.
• There are different machines determining the band gaps of the perfect and defective La0.5Sr0.5MnO3.

The structural, magnetic and electronic properties of the perfect and defective La0.5Sr0.5MnO3 are investigated by performing the first-principle calculation. The negative value of formation energy implies the formation process of N atom substituting O atom in La0.5Sr0.5MnO3 are exothermic, indicating this structure could stably exist. Both the perfect and defective La0.5Sr0.5MnO3 are found to be half-metallic ferromagnets and potential in spintronic devices. For La0.5Sr0.5MnO3, the gap width of 2.902 eV is extremely wide. While the gap width decrease with existing the defect and the gap width decreases according to the order of the perfect, VO and DN. There are different mechanisms determining the band gaps of the perfect and defective La0.5Sr0.5MnO3.