Periodically poled KTA crystal investigated using coherent X-ray beams

The distribution of inverted ferroelectric domains on the surface and withi n the bulk of a periodically poled KTA (KTiOAsO4) single crystal has been o bserved using a simple X-ray diffraction imaging setup which takes advantag e of the highly coherent beams available at a third-generation synchrotron source, such as the ESRF. This technique allows one to reveal the phase dif ference between the waves that are Bragg diffracted from adjacent domains v ia free-space propagation (Fresnel diffraction). The phase difference of th e diffracted waves is mainly produced by the difference in phases of the st ructure factors involved, and contains precise structural information about the nature of the domain walls.