Partial decoupling between strain and polarization in mono-oriented Pb(Zr0.2Ti0.8)O3 thin film

The structural evolution of epitaxial mono-oriented (i.e., with the c axis perpendicular to the interface) ferroelectric Pb(Zr0.2Ti0.8)O3 thin film has been investigated, using high-resolution, temperature dependent, x-ray diffraction. The full set of lattice parameters was obtained; it allowed to estimate the variation of the polarization as a function of temperature, underlying the difference between the polarization-induced tetragonality and the elastic one. The temperature evolution of the misfit strain has been calculated and found to be in good agreement with the theoretical temperature-misfit strain phase diagram.