title: Size-dependent polar ordering in colloidal GeTe nanocrystals.
abstract: The question of the nature and stability of polar ordering in nanoscale ferroelectrics is examined with colloidal nanocrystals of germanium telluride (GeTe). We provide atomic-scale evidence for room-temperature polar ordering in individual nanocrystals using aberration-corrected transmission electron microscopy and demonstrate a reversible, size-dependent polar-nonpolar phase transition of displacive character in nanocrystal ensembles. A substantial linear component of the distortion is observed, which is in contrast with theoretical reports predicting a toroidal state.
authors.affiliation: Department of Materials Science and Engineering, University of California , Berkeley, Berkeley, California 94720, United States.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Polking
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Urban
authors.forename: Delia J
authors.initials: DJ
authors.lastname: Milliron
authors.forename: Haimei
authors.initials: H
authors.lastname: Zheng
authors.forename: Emory
authors.initials: E
authors.lastname: Chan
authors.forename: Marissa A
authors.initials: MA
authors.lastname: Caldwell
authors.forename: Simone
authors.initials: S
authors.lastname: Raoux
authors.forename: Christian F
authors.initials: CF
authors.lastname: Kisielowski
authors.forename: Joel W
authors.initials: JW
authors.lastname: Ager
authors.forename: Ramamoorthy
authors.initials: R
authors.lastname: Ramesh
authors.forename: A Paul
authors.initials: AP
authors.lastname: Alivisatos