02142nas a2200397 4500008004100000022001300041245008000054210006900134260002800203490000600231520107100237653001201308653001201320653001401332653001601346653002801362653002401390653001201414653001201426653001101438653001501449653002101464653001401485100001501499700001401514700001201528700001401540700001501554700001201569700001401581700001601595700001601611700002401627700001601651856007701667 2018 eng d a2041172300aConfigurable topological textures in strain graded ferroelectric nanoplates0 aConfigurable topological textures in strain graded ferroelectric bNature Publishing Group0 v93 aTopological defects in matter behave collectively to form highly non-trivial structures called topological textures that are characterised by conserved quantities such as the winding number. Here we show that an epitaxial ferroelectric square nanoplate of bismuth ferrite subjected to a large strain gradient (as much as 105 m-1) associated with misfit strain relaxation enables five discrete levels for the ferroelectric topological invariant of the entire system because of its peculiar radial quadrant domain texture and its inherent domain wall chirality. The total winding number of the topological texture can be configured from - 1 to 3 by selective non-local electric switching of the quadrant domains. By using angle-resolved piezoresponse force microscopy in conjunction with local winding number analysis, we directly identify the existence of vortices and anti-vortices, observe pair creation and annihilation and manipulate the net number of vortices. Our findings offer a useful concept for multi-level topological defect memory. © 2018 The Author(s).10aArticle10abismuth10achirality10adestruction10adiscrete element method10aelectrical property10aferrite10aleisure10amemory10amicroscopy10apiezoelectricity10avorticity1 aKim, K.-E.1 aJeong, S.1 aChu, K.1 aLee, J.H.1 aKim, G.-Y.1 aXue, F.1 aKoo, T.Y.1 aChen, L.-Q.1 aChoi, S.-Y.1 aRamesh, Ramamoorthy1 aYang, C.-H. uhttps://rameshlab.lbl.gov/publications/configurable-topological-textures02196nas a2200457 4500008004100000022001300041245006900054210006900123260003000192300001400222490000700236520091400243653001201157653001601169653002101185653003101206653002101237653002101258653002401279653002701303653001701330653001701347653001501364653003001379653002601409653001301435653001601448100001301464700002001477700001201497700001501509700001601524700001601540700001701556700001601573700001601589700001701605700002401622700001601646856007601662 2017 eng d a1530698400aStability of Polar Vortex Lattice in Ferroelectric Superlattices0 aStability of Polar Vortex Lattice in Ferroelectric Superlattices bAmerican Chemical Society a2246-22520 v173 aA novel mesoscale state comprising of an ordered polar vortex lattice has been demonstrated in ferroelectric superlattices of PbTiO3/SrTiO3. Here, we employ phase-field simulations, analytical theory, and experimental observations to evaluate thermodynamic conditions and geometric length scales that are critical for the formation of such exotic vortex states. We show that the stability of these vortex lattices involves an intimate competition between long-range electrostatic, long-range elastic, and short-range polarization gradient-related interactions leading to both an upper and a lower bound to the length scale at which these states can be observed. We found that the critical length is related to the intrinsic domain wall width, which could serve as a simple intuitive design rule for the discovery of novel ultrafine topological structures in ferroic systems. © 2017 American Chemical Society.10aArticle10acompetition10aCrystal lattices10aFerroelectric superlattice10aferroelectricity10aGeometric length10aNeodymium compounds10aPhase-field simulation10aPolar vortex10aPolarization10asimulation10aSuperconducting materials10aTopological structure10aTopology10aVortex flow1 aHong, Z.1 aDamodaran, A.R.1 aXue, F.1 aHsu, S.-L.1 aBritson, J.1 aYadav, A.K.1 aNelson, C.T.1 aWang, J.-J.1 aScott, J.F.1 aMartin, L.W.1 aRamesh, Ramamoorthy1 aChen, L.-Q. uhttps://rameshlab.lbl.gov/publications/stability-polar-vortex-lattice-0