Microstructural investigation of La2Ti2O7 thin films grown by MBE

摘要

Abstract: In the La-Ti-O system many phases with different structures exist depending on the actual oxygen content. Starting from LaTiO$-3$/, which has an orthorhombic unit cell, to the monoclinic La$-2$/Ti$-2$/O$-7$/ structure, first semiconducting, then metallic and finally ferroelectric characteristics can be obtained at room temperature. Recent transmission electron microscopy studies of the bulk materials showed that the transformation of the LaTiO$-3$/ structure to La$-2$/Ti$-2$/O$-7$/ is based on the insertion of an additional oxygen plane in the $LFBC@110$RTBC perovskite planes. A controlled insertion of this oxygen plane would allow heterostructures to be grown that exhibit different physical properties but have perfect chemical compatibility. Here, we report on our results of epitaxially grown thin films of La$-2$/Ti$-2$/O$-7$/ on (110)-oriented SrTiO$-3$/ and LaAlO$-3$/ substrates using sequential deposition of La and Ti under a beam of atomic oxygen. The epitaxial behavior and the microstructural properties of these films were investigated by transmission electron microscopy. !21