Fig. 1.

Self-organized arrays of electric polarization textures in (PbTiO₃)_n/(SrTiO₃)_n superlattices exhibit a chiral RSXD pattern. (A) These polar arrays produce diffraction satellites that decorate the specular reflection along the lateral direction, [100]_χ, for X-rays tuned near the titanium L₃ edge. Specular scattering plane is shown in blue. Red and blue helices illustrate opposing circular polarizations of incident X-rays. Sample azimuth is indicated by Φ. (B) (Upper) Line cut of scattered intensity versus lateral momentum transfer (q_lateral) using right- (red) and left-circularly (blue) polarized X-rays for n = 16. (Lower) XCD is the difference in intensity for the two helicities. (C) (Upper) Resonance profiles through the titanium L_3,2 edges at q_lateral = +q_{χ_pair} for both X-ray helicities (red and blue) and (Lower) their XCD (green) for n = 14. Fluorescence absorption spectrum (black curve in Upper) shows electronic states similar to that of Pb(Zr_0.2Ti_0.8)O₃ (14). (D) Map of XCD intensity at q_lateral = +q_{χ_pair} across an n = 14 sample. Regions of positive (negative) XCD indicate where chiral polar arrays have positive (negative) helicity.