Identification of inversion domains in KTiOPO4 via resonant X-ray diffraction

A novel method is presented for the identification of the absolute crystal-lographic structure in multi-domain polar materials such as ferroelectric KTiOPO4. Resonant (or ‘anomalous’) X-ray diffraction spectra collected across the absorption K edge of Ti (4.966 keV) on a single Bragg reflection demonstrate a huge intensity ratio above and below the edge, providing a polar domain contrast of 270. This allows one to map the spatial domain distribution in a periodically inverted sample, with a resolution of 1 mm achieved with a microfocused beam. This non-contact, non-destructive technique is well suited for samples of large dimensions (in contrast with traditional resonant X-ray methods based on diffraction from Friedel pairs), and its potential is particularly relevant in the context of physical phenomena connected with an absence of inversion symmetry, which require characteriza-tion of the underlying absolute atomic structure (such as in the case of magnetoelectric coupling and multiferroics). 1