%0 Journal Article
%A Park, D.
%A Herpers, Anja
%A Menke, Tobias
%A Heidelmann, Markus
%A Houben, Lothar
%A Dittmann, Regina
%A Mayer, Joachim
%T Studies of Local Structural Disortions in Strained Ultrathin BaTiO3 Films sing Scanning Transmission Electron Microscopy
%J Microscopy and microanalysis
%V 20
%@ 1431-9276
%C New York, NY
%I Cambridge University Press
%M FZJ-2014-06431
%P 740 -747
%D 2014
%X Ultrathin ferroelectric heterostructures (SrTiO3/BaTiO3/BaRuO3/SrRuO3) were studied by scanning transmission electron microscopy (STEM) in terms of structural distortions and atomic displacements. The TiO2-termination at the top interface of the BaTiO3 layer was changed into a BaO-termination by adding an additional BaRuO3 layer. High-angle annular dark-field (HAADF) imaging by aberration-corrected STEM revealed that an artificially introduced BaO-termination can be achieved by this interface engineering. By using fast sequential imaging and frame-by-frame drift correction, the effect of the specimen drift was significantly reduced and the signal-to-noise ratio of the HAADF images was improved. Thus, a quantitative analysis of the HAADF images was feasible, and an in-plane and out-of-plane lattice spacing of the BaTiO3 layer of 3.90 and 4.22 Å were determined. A 25 pm shift of the Ti columns from the center of the unit cell of BaTiO3 along the c-axis was observed. By spatially resolved electron energy-loss spectroscopy studies, a reduction of the crystal field splitting (CFS, ΔL3=1.93 eV) and an asymmetric broadening of the e g peak were observed in the BaTiO3 film. These results verify the presence of a ferroelectric polarization in the ultrathin BaTiO3 film.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000339158700014
%R 10.1017/S1431927614000518
%U https://juser.fz-juelich.de/record/173018