Atomic-scale mechanisms of ferroelastic domain-wall-mediated ferroelectric switching

Polarization switching in ferroelectric thin films occurs via nucleation and growth of 180° domains through a highly inhomogeneous process in which the kinetics are largely controlled by defects, interfaces and pre-existing domain walls. Here we present the first real-time, atomic-scale observations and phase-field simulations of domain switching dominated by pre-existing, but immobile, ferroelastic domains in Pb(Zr 0.2 Ti 0.8 )O 3 thin films. Our observations reveal a novel hindering effect, which occurs via the formation of a transient layer with a thickness of several unit cells at an otherwise charged interface between a ferroelastic domain and a switched domain. This transient layer possesses a low-magnitude polarization, with a dipole glass structure, resembling the dead layer. The present study provides an atomic level explanation of the hindering of ferroelectric domain motion by ferroelastic domains. Hindering can be overcome either by applying a higher bias or by removing the as-grown ferroelastic domains in fabricated nanostructures. In ferroelectric thin films, ferroelastic domains affect the features of polarization switching. Gao et al. perform real-time transmission electron microscopy measurements and show that ferroelastic domains can hinder the switching via formation of a transient interface layer with a dipole glass structure.