The half-metallic ferromagnetic characters of (001)-oriented thin films of the double perovskite Pb2FeMoO6

• An outwards relaxation is observed for several surface layers.
• The rumpling of the PbO-layer is larger than that of the FeMoO4 layer.
• The O atom is closer to the adjacent Mo atom than to the adjacent Fe atom.
• Half-metallic nature is maintained for three (001)-oriented thin films of Pb2FeMoO6.
• Delocalized spin densities around Fe on the first layer lead to a smaller moment.

The structural, electronic and magnetic properties of the three possible terminations of the (001)-oriented thin film of the double perovskite Pb2FeMoO6, 10-L FeMoO4 and PbO terminated, 9-L FeMoO4 terminated and 11-L PbO terminated, have been studied by using the first-principles calculations. It is found that, firstly an outwards relaxation is observed for several layers near surface and the relaxed fractional rumpling s of the PbO layer is larger than that of the adjacent FeMoO4 layer and both have a decrease tend from surface layer to inner layer. Second, whether parallel to or perpendicular to the surface, the MoO bond length is always shorter than the adjacent FeO bond length. Thirdly, the half-metallic ferromagnetic (HM-FM) character ensures these three terminations of the (001)-oriented thin films of the double perovskite Pb2FeMoO6 a potential application in magnetoresistive and spintronics devices. Fourth, delocalized distribution of the spin charge densities around the Fe atoms on the first FeMoO4 layer leads to a smaller magnetic moment of the Fe atoms on the first FeMoO4 layer than the inner Fe atoms.