Electron energy-loss spectroscopy is used to map composition and electronic states in epitaxial La2/3Ca1/3MnO3 films grown on SrTiO3 (001) and (110) substrates. It is found that in partially relaxed (110) films cationic composition and valence state of Mn3+/4+ ions are preserved across the film thickness. In contrast, in fully strained (001) films, the Ca/La ratio gradually changes across the film, being La rich at film/substrate interface and La depleted at free surface; Mn valence state changes accordingly. These observations suggest that a strongly orientation-dependent adaptative composition mechanism dominates stress accommodation in manganite films and provides microscopic understanding of their dissimilar magnetic properties.
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Estradé et al. (2008) studied this question.
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