Intrinsic ferroelectric properties of strained tetragonal PbZr0.2Ti0.8O3   obtained on layer-by-layer grown, defect-free single crystalline films
  PbZrxTi1-xO3 (PZT) is one of the technologically most important ferroelectric materials. Bulk single-domain single crystals of PZT have never been synthesized for a significant compositional range across the solid-solution phase diagram. This leaves the fundamental properties of PZT under debate. Synthesis of defect-free single crystalline films enables us to unambiguously determine the intrinsic quantities that describe ferroelectric materials, such as spontaneous polarization and dielectric constant. Defect-free single crystalline, strained PbZr0.2Ti0.8O3 thin films were grown by pulsed-laser deposition (PLD) onto vicinal SrTiO3 (001) single crystal substrates. Single crystalline SrRuO3 films fabricated by PLD were employed as bottom electrode. The PZT films have square shape hysteresis loops and remnant polarization values of up to Pr= 110 micro C/cm2, which is considerably higher than the theoretical value predicted for (unstrained) bulk single crystalline PZT of the investigated composition. The films have a dielectric constant eps33= 90 and a piezoelectric coefficient d33= 50 pm/V. 
Ionela Vrejoiu, Gwenael Le Rhun, Lucian Pintilie, Dietrich Hesse,   Marin Alexe, and Ulrich Goesele