Probing ferroelectricity in PbZr0.2 Ti0.8 O 3 with polarized soft x rays

The reduction in symmetry associated with the onset of ferroelectric order in PbZr0.2 Ti0.8 O3 (PZT) thin films leads to a pronounced difference at the Ti L3,2 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. © 2010 The American Physical Society.