Direct observation of continuous electric dipole rotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O
March 1, 2011
by Chun-Lin Jia, Knut Urban, Marin Alexe, Dietrich Hesse, and Ionela Vrejoiu
Low-dimensional ferroelectric structures are a promising basis for the next generation ofultrahigh-density nonvolatile memory devices. Depolarising fields, created by incompletelycompensated charges at the surfaces and interfaces, depress the polarisation of such structures.Theory suggests that under conditions of uncompensated surface charges, local dipoles canorganise in flux-closure structures in thin films and vortex structures in nano-sized ferroelectrics,reducing depolarising fields. However, the continuous rotation of the dipoles required in vortexstructures and the behaviour of unit cell dipoles in flux-closure structures have so far not beenexperimentally established.
By aberration-corrected transmission electron microscopy with the instrument operated under NCSI conditions, experimental evidence for a continuous rotation of the dipoles closing the flux of 180° domainsin a ferroelectric perovskite thin film was found. In this way, an interface-near region within Pb(Zr,Ti)O films was observed where the local dipoles rotate continuously forming a flux-closure structure connecting two 180° domains.
Chun-Lin Jia, Knut Urban, Marin Alexe, Dietrich Hesse, and Ionela Vrejoiu: Direct observation of continuous electric dipole rotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O, Science 331 (2011) 1420-1423.