X-ray scattering evidence for the structural nature of fatigue in epitaxial Pb(Zr, Ti)O₃ films

We have probed the microscopic distribution of 180° domains as a function of switching history in 40 nm epitaxial films of Pb(Zr_0.30Ti_0.70)O₃ by analyzing interference effects in the x-ray scattering profiles. These as-grown films exhibit voltage offsets (imprint) in the polarization hysteresis loops, coupled with a strongly preferred polarization direction in the virgin state. Our x-ray results are consistent with models attributing the loss of switchable polarization to the inhibition of the formation of oppositely polarized domains in a unipolar matrix. Using such model epitaxial films, we demonstrate that different microscopic ensembles of domains resulting from, for example, fatigue, may be resolved by this technique.