Probing ferroelectricity in PbZr0.2Ti0.8O3 with polarized soft x rays

The reduction in symmetry associated with the onset of ferroelectric order in PbZr0.2Ti0.8O3 (PZT) thin films leads to a pronounced difference at the Ti L-3,L-2 absorption edges between spectra measured with the x-ray linear polarization perpendicular and parallel to the ferroelectric polarization. We introduce a general method to analyze the observed difference spectra using atomic multiplet calculations. Moreover, we find experimental evidence for structural changes in PZT induced by the reversal of the ferroelectric polarization.