Domain- and symmetry-transition origins of reduced nanosecond piezoelectricity in ferroelectric/dielectric superlattices

Complex-oxide superlattices (SLs) with atomic-scale periodicity have dynamical properties that are distinct from thin films of uniform composition. The origins of these properties are closely related to the dynamics of polarization domains and to field-driven changes in the symmetries resulting from interfacial coupling between different components. These dynamics are apparent at timescales from a few nanoseconds to several milliseconds in experiments probing the piezoelectricity of a ferroelectric/dielectric BaTiO3(BTO)/CaTiO3 (CTO) SL using time-resolved x-ray microdiffraction. At the 100 ns timescale, the piezoelectric distortion is approximately ten times smaller than in the millisecond regime. This reduced piezoelectricity at short timescales is not observed in previously studied PbTiO3/SrTiO3 SLs or compositionally uniform ferroelectrics such as tetragonal compositions of Pb(Zr,Ti)O3. The unusual behavior of the BTO/CTO SL can be linked to the switching of a nanodomain state into a uniform polarization state or to a field-induced crystallographic symmetry transition. A comparison of the results 5 These authors have contributed equally to this work. 6 Author to whom any correspondence should be addressed. New Journal of Physics 14 (2012) 013034 1367-2630/12/013034+12$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft