Structure and polarization in epitaxial ferroelectric PbZr0.52Ti0.48O3/YBa2Cu3O7−x/Nd:YAlO3 thin films

We fabricate epitaxial ${\mathrm{PbZr}}_{\mathrm{0.52}}{\mathrm{Ti}}_{\mathrm{0.48}}{\mathrm{O}}_{\mathrm{3}}{\mathrm{/YBa}}_{\mathrm{2}}{\mathrm{Cu}}_{\mathrm{3}}{\mathrm{O}}_{\text{7−x}}$ submicron film ferroelectric/superconductor heterostructures on the single-crystal ${\mathrm{YAlO}}_{\mathrm{3}}{\mathrm{+1\%Nd}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ substrate by the pulsed laser deposition technique. Frequency independent low loss $\tan \text{\hspace{0.17em}δ=0.04}$ and dielectric constant of 950, high electric resistivity ρ ${\mathrm{(150\hspace{0.17em}kV/cm)=6\times 10}}^{\mathrm{11}}\mathrm{\Omega \hspace{0.17em}cm},$ remnant polarization of $\text{32\hspace{0.17em}μ}{\mathrm{C/cm}}^{\mathrm{2}},$ no visible fatigue after ${10}^7$ short bipolar pulses switching indicate excellent electrical performance of the new capacitor structure. The slight crystallite polar axis misalignment and depolarizing effect were found to be responsible for the shape of the apparent polarization loop. The only fitting parameter depolarizing coefficient ${\text{N=2.37×10}}^{\text{−4}}$ gives the best fit between theory and experimental data and corresponds to prolate ellipsoidal shaped crystallites with the length-to-diameter ratio of 140.