Evidence of Mn-Ion Structural Displacements Correlated to Oxygen Vacancies in La0.7Sr0.3MnO3 Interfacial Dead Layers

International audienceProperties of half-metallic manganite thin films depend on the composition and structure in the atomic scale, and consequently, their potential functional behaviour can only be based on fine structure characterization. By combining advanced transmission electron microscopy methods, electron energy loss spectroscopy, density functional theory (DFT) calculations, and multislice image simulations, we obtained evidence of a 7 nm-thick interface layer in La0.7Sr0.3MnO3 (LSMO) thin films, compatible with the formation of well-known dead layers in manganites, with an elongated out-of-plane lattice parameter, and structural and electronic properties well distinguished from the bulk of the film. We observed, for the first time, a structural shift of Mn ions coupled with oxygen vacancies and a reduced Mn valence state within such layer. Understanding the correlation between oxygen vacancies, the Mn oxidation state, and Mn ions displacements is a prerequisite to engineer the magneto-transport properties of LSMO thin films