Fig. 2.

Mirrored diffraction vectors detect opposite rotational patterns in chiral textures. RSXD is sensitive to anisotropic TiO₆ distortions, so that a helical rotation of the electric polarization can produce RSXD peaks with antisymmetric XCD. (A) Conical blue arrows indicate the direction of polarization, which rotates helically along the lateral direction, [100]_χ. The distorted perovskite cell is depicted for several orientations, as is the distorted TiO₆ octahedron for an up-polarized unit cell. (B) The cyclic modulation of polarization for this same helix is highlighted by folding the lateral dimension into a circle. The diffraction vector with q_lateral > 0 (red arrow) senses a clockwise helical rotation of polarization, whereas the diffraction vector with q_lateral < 0 (blue arrow) detects a counterclockwise rotation.