Extended Data Fig. 2: Comparing ABF images taken at different sample regions.
From: Electron ptychography reveals a ferroelectricity dominated by anion displacements
The contrast of ABF images relies heavily on the details of the diffraction conditions and is most sensitive to the sample’s surface structure. (a-c) show ABF images (inverted contrast) taken at different regions of the NaNbO3/DyScO3 sample. The images show differences in the positions and contrast of the different atoms, arising predominantly from variations in sample thickness. For very thin regions in the sample, ABF might give qualitatively the correct structure as can be seen in (c). But without prior knowledge of the correct structure, ABF images are unreliable as images taken in different regions of the sample can show very different characteristics.
