The role of as-grown defects and electrode materials on polarization orientation of Pb(Zr0.52Ti0.48)O3 on YBa2Cu3O7-x

A preferred polarization orientation in the as-grown Pb(Zr0.52Ti0.48)O3/YBa2Cu3O7-x (PZT/YBCO) system has been observed which is directed from PZT toward YBCO. This behavior in PZT is attributed to O and Pb vacancies created in as-grown YBCO and PZT. The interaction of different electrode materials at the top and bottom of PZT with these defects and its influence on the hysteresis loop of the ferroelectric material result in asymmetry in the system and consequently preferential polarization. The preferred state of polarization is reversible from room temperature up to the Curie temperature of PZT (∝350 C), while the less preferred polarization is only stable up to 220 C and switches to the preferred state at this temperature. (orig.)