title: Valence changes and structural distortions in "charge ordered" manganites quantified by atomic-scale scanning transmission electron microscopy.
abstract: We investigate the microscopic nature of the "charge ordering" modulation in mixed-valent manganites in real space using scanning transmission electron microscopy. The modulation in Bi0.5Sr0.4Ca0.1MnO3 has a uniform periodicity appearing as stripes in high angle annular dark field images. Geometric phase analysis shows the modulation to be a displacement wave with transverse amplitude (0.008+/-0.001)a and longitudinal amplitude (0.003+/-0.001)a. Series of energy loss spectra taken across the stripes show no periodic changes and place an upper bound of +/-0.04 on any valence changes of the Mn ions.
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Loudon
authors.forename: L Fitting
authors.initials: LF
authors.lastname: Kourkoutis
authors.forename: J S
authors.initials: JS
authors.lastname: Ahn
authors.forename: C L
authors.initials: CL
authors.lastname: Zhang
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.forename: D A
authors.initials: DA
authors.lastname: Muller