Local clusters in a distorted rocksalt gete crystal found by X-ray fluorescence holography

A Ge Kα X-ray fluorescence holography (XFH) measurement was performed on a single-crystal GeTe film with a deformed rocksalt (rhombohedral) lattice, for which careful analyses and observations of the reconstructed atomic images were needed. The three-dimensional atomic images obtained around the central Ge atom were compared with the theoretical images obtained from a simulated hologram in the full sphere range and in the limited θ range (0 < θ < 74°),as in the experiment. It was found that reliable atomic images were realized only when neighboring atoms are located on the surface side of the central Ge atom. GeTe₃ clusters were found by XFH, which cannot be easily detected by diffraction, and confirmed by ab initio molecular dynamics simulation.