title: Configuration and local elastic interaction of ferroelectric domains and misfit dislocation in PbTiO3/SrTiO3epitaxial thin films.
abstract: We have studied the strain field around the 90° domains and misfit dislocations in PbTiO3/SrTiO3(001) epitaxial thin films, at the nanoscale, using the geometric phase analysis (GPA) combined with high-resolution transmission electron microscopy (HRTEM) and high-angle annular dark field--scanning transmission electron microscopy (HAADF-STEM). The films typically contain a combination ofa/c-mixed domains and misfit dislocations. The PbTiO3layer was composed from the two types of thea-domain (90° domain): a typicala/c-mixed domain configuration wherea-domains are 20-30 nm wide and nano sized domains with a width of about 3 nm. In the latter case, the nano sizeda-domain does not contact the film/substrate interface; it remains far from the interface and stems from the misfit dislocation. Strain maps obtained from the GPA of HRTEM images show the elastic interaction between thea-domain and the dislocations. The normal strain field and lattice rotation match each other between them. Strain maps reveal that thea-domain nucleation takes place at the misfit dislocation. The lattice rotation around the misfit dislocation triggers the nucleation of thea-domain; the normal strains around the misfit dislocation relax the residual strain ina-domain; then, thea-domain growth takes place, accompanying the introduction of the additional dislocation perpendicular to the misfit dislocation and the dissociation of the dislocations into two pairs of partial dislocations with an APB, which is the bottom boundary of thea-domain. The novel mechanism of the nucleation and growth of 90° domain in PbTiO3/SrTiO3epitaxial system has been proposed based on above the results.
authors.affiliation: Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kiguchi
authors.affiliation: Department of Materials Science, Tohoku University, Sendai, Miyagi 980-8579, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Aoyagi
authors.affiliation: Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ehara
authors.affiliation: Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Funakubo
authors.affiliation: Department of Materials, Physics and Energy Engineering, Nagoya University, Nagoya, Aichi 464-8603, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Usami
authors.affiliation: Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan.
authors.forename: Toyohiko J
authors.initials: TJ
authors.lastname: Konno
keywords: 90° domain; HRTEM; PbTiO3; elastic interaction; ferroelectric thin film; geometric phase analysis; misfit dislocation; strain