Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 (67/33) thin films with large tunable self-bias field controlled by a PbZr1−xTixO3 interfacial layer

Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 200 nm thick, (001) oriented, perovskite phase-pure films were grown on a range of PbZr1−xTixO3 buffer layers (x = 0.2–0.8) and sandwiched between SrRuO3 electrodes on (001) SrTiO3 substrates to form a ferroelectric capacitor structure. Devices without a buffer layer or with a buffer layer of highly tetragonal PbZr1−xTixO3 show very large self-bias fields up to 1.0 × 107 V/m. These self-bias fields correlate with strain gradient layers near the bottom electrode observed in these devices only. The large self-bias was explained quantitatively in terms of the flexoelectric effect.