Microstructure of La0.7Sr0.3MnO3/Ba0.7Sr0.3TiO3/La0.7Sr0.3MnO3 epitaxial films grown on (0 0 1) SrTiO3 substrate

The microstructure of La0.7Sr0.3MnO3/Ba0.7Sr0.3TiO3/La0.7Sr0.3MnO3 (LSMO/BST/LSMO) thin films epitaxially grown on (001) SrTiO3 substrate by pulsed laser deposition was investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Both threading dislocations (TDs) and misfit dislocations (MDs) were found in the films. Diffraction contrast and convergent beam electron diffraction (CBED) analyses reveal that the TDs are mostly pure-screw-type with Burgers vectors b=[001]. The MDs of edge character are located at both top LSMO/BST and bottom LSMO/BST interfaces with predominant [100] and [101] Burgers vectors. The average spacings between neighboring MDs at both LSMO/BST interfaces are smaller than that derived from lattice mismatch, which indicates the films are partly relaxed.