Ferroelectric polarization reversal via successive ferroelastic transitions

Switchable polarization makes ferroelectrics a critical component in memories, actuators and electro-optic devices, and potential candidates for nanoelectronics. Although many studies of ferroelectric switching have been undertaken, much remains to be understood about switching in complex domain structures and in devices. In this work, a combination of thin-film epitaxy, macro- and nanoscale property and switching characterization, and molecular dynamics simulations are used to elucidate the nature of switching in PbZr0.2Ti0.8O3 thin films. Differences are demonstrated between (001)-/(101)- and (111)- oriented films, with the latter exhibiting complex, nanotwinned ferroelectric domain structures with high densities of 90 degrees domain walls and considerably broadened switching characteristics. Molecular dynamics simulations predict both 180 degrees (for (001)-/(101)- oriented films) and 90 degrees multi-step switching (for (111)- oriented films) and these processes are subsequently observed in stroboscopic piezoresponse force microscopy. These results have implications for our understanding of ferroelectric switching and offer opportunities to change domain reversal speed.