Field-Dependent Domain Distortion and Interlayer Polarization Distribution in PbTiO3/SrTiO3 Superlattices

The remnant polarization of weakly coupled ferroelectric-dielectric superlattices is distributed unequally between the component layers, and as a result the components respond differently to applied electric fields. The difference is apparent in both the nanometer-scale structure of striped polarization domains and in the development of piezoelectric strain and field-induced polarization. Both effects are probed with in situ time-resolved synchrotron x-ray diffraction in a PbTiO3/SrTiO3 superlattice in fields up to 2.38 MV/cm. Domains are initially distorted to increase the polarization in the SrTiO3 layer while retaining the striped motif. The subsequent transformation to a uniform polarization state at a later time leads to piezoelectric expansion dominated by the field-induced polarization of the SrTiO3 layers. The results are consistent with theoretical predictions of the field dependence of the domain structure and electrical polarization. DOI: 10.1103/PhysRevLett.110.047601