A study of the domain structure of epitaxial La1-xCaxMnO3 films by high-resolution transmission electron microscopy

Thin films of La1-xCaxMnO3(LCMO), deposited by laser ablation on a suitably heated SrTiO3 substrate, exhibit a remarkable microstructure, which has be en studied by high-resolution electron microscopy and electron diffraction. In direct contact with the SrTiO3 substrate a thin featureless, perfectly coherent La1-xCaxMnO3 layer is formed. Subsequently on top of this first la yer a second thicker layer is deposited; it has a columnar microstructure. These columns, parallel to the interface normal, are in fact prismatic anti phase domains. Their formation is attributed to the introduction of chemica l faults during the film growth process. Islands of rocksalt-type MnO struc ture, nucleated within the regular La-O layer of the LCMO structure, initia te the formation of the prismatic antiphase domains. Models of the domain b oundaries and of the film-substrate interface are proposed and verified by the comparison of observed and computer-simulated images. A growth mechanis m for the domain structure is suggested.