Self-assembly and switching in ferroelectrics and multiferroics

Abstract

Molecules of low symmetry often self-assemble in Nature to produce mesoscopic structures of symmetry higher than their constituent building blocks, including “super-cubic” structures. Such self-assembled hexagonal domains have recently been observed in orthorhombic polymeric ferroelectrics, and resemble those known in surfactants and in magnetic bubble domains. Ferroelastic nanodomains in ferroelectric films also self-assemble into bundles of tens of nanometers diameter within each ferroelectric domain that locally average polarization and strain to small values. Under applied stress or electric or magnetic field these bundles exhibit higher mobility than expected and switch polarization via magnetostriction plus piezoelectricity. The phenomenon is analogous to Anderson's 1962 model of “vortex bundle” motion in Type-II superconductors.