Vortex Polarization States in Nanoscale Ferroelectric Arrays

Abstract

Two-dimensional arrays of ferroelectric lead zirconate titanate (PZT) nanodots were fabricated using pulsed laser deposition through ultrathin anodic aluminum oxide membrane stencil masks. The static distribution of polarization configurations was investigated using in- and out-of-plane piezoresponse force microscopy (PFM). The observed presence of an in-plane polarization component in nominally (001) oriented PZT suggests the existence of a significant deviation from the regular tetragonal structure that allows the formation of complex core-polarization states. Core-polarization states may indicate the presence of quasi-toroidal polarization ordering. The experimental results are compared with a theoretical model to determine the fingerprint of a vortex polarization state in PFM.

Ferroelectric nanodomains in epitaxial PbTiO3 films grown on SmScO3 and TbScO3 substrates

“…[1][2][3][4][5][6][7][8] Various special patterns were seen, such as ferroelectric flux closure and quadrupolar vortex arrangements. [9][10][11][12][13][14][15][16][17][18][19] Most peculiar domain arrangements were found in theoretical model simulations conducted for rather extreme geometries of dimensions comparable with domain wall thickness, such as ultrathin films, short-period superlattices and ferroelectric nanodots. [9][10][11]13 Domain walls in ferroelectric films with an order of magnitude larger thickness (of the order of 100 nm) are expected to bear mostly bulk material properties.…”

“…[9][10][11][12][13][14][15][16][17][18][19] Most peculiar domain arrangements were found in theoretical model simulations conducted for rather extreme geometries of dimensions comparable with domain wall thickness, such as ultrathin films, short-period superlattices and ferroelectric nanodots. [9][10][11]13 Domain walls in ferroelectric films with an order of magnitude larger thickness (of the order of 100 nm) are expected to bear mostly bulk material properties. Nevertheless, the necessity of stress and depolarization charge compensation at 100 nm scales implies presence of a much higher density of domain walls and this can also make conditions for certain nanoscale-specific domain arrangements, different from typical bulk domain structures.…”

Individual switching of film-based nanoscale epitaxial ferroelectric capacitors

“…There have been many efforts to fabricate and analyze individually addressable nanoscale ferroelectric capacitors. [4][5][6][7][8][9][10][11][12] Several different fabrication methods such as chemical solution deposition, focused ion-beam ͑FIB͒, and e-beam lithography have been used for ferroelectric nanostructure fabrication. [6][7][8][9][10][11][12][13][14][15] FIB has been almost exclusively used to fabricate ferroelectric capacitors.…”

Super switching and control of in-plane ferroelectric nanodomains in strained thin films

“…Within the last 5 years, several experimental studies have been focused on the effect of geometrical confinement on novel nanoscale domain patterns 3,4 , especially in lamellae and small-scale dots from bulk single crystals of BaTiO 3 (refs 12-16), PbZr (1 À x) Ti x O 3 (PZT) 17 and Pb(Zn 1/3 Nb 2/3 ) (1 À x) Ti x O 3 (PZN-PT) 18 . A few studies were also conducted on disk-shaped thin film capacitor structures of PZT 19,20 . Exotic dipole arrangements have been evidenced but their formation remains not fully understood.…”