title: Ferroelectric order in individual nanometre-scale crystals.
abstract: Ferroelectricity in finite-dimensional systems continues to arouse interest, motivated by predictions of vortex polarization states and the utility of ferroelectric nanomaterials in memory devices, actuators and other applications. Critical to these areas of research are the nanoscale polarization structure and scaling limit of ferroelectric order, which are determined here in individual nanocrystals comprising a single ferroelectric domain. Maps of ferroelectric structural distortions obtained from aberration-corrected transmission electron microscopy, combined with holographic polarization imaging, indicate the persistence of a linearly ordered and monodomain polarization state at nanometre dimensions. Room-temperature polarization switching is demonstrated down to ~5 nm dimensions. Ferroelectric coherence is facilitated in part by control of particle morphology, which along with electrostatic boundary conditions is found to determine the spatial extent of cooperative ferroelectric distortions. This work points the way to multi-Tbit/in(2) memories and provides a glimpse of the structural and electrical manifestations of ferroelectricity down to its ultimate limits.
authors: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Mark J
authors: MJ
authors: Polking
authors: Myung-Geun
authors: MG
authors: Han
authors: Amin
authors: A
authors: Yourdkhani
authors: Valeri
authors: V
authors: Petkov
authors: Christian F
authors: CF
authors: Kisielowski
authors: Vyacheslav V
authors: VV
authors: Volkov
authors: Yimei
authors: Y
authors: Zhu
authors: Gabriel
authors: G
authors: Caruntu
authors: A Paul
authors: AP
authors: Alivisatos
authors: Ramamoorthy
authors: R
authors: Ramesh