Fluorescence X‐ray absorption spectroscopy using a Ge pixel array detector: application to high‐temperature superconducting thin‐film single crystals

A Ge pixel array detector with 100 segments was applied to fluorescence X-ray absorption spectroscopy, probing the local structure of high-temperature superconducting thin-film single crystals (100 nm in thickness). Independent monitoring of pixel signals allows real-time inspection of artifacts owing to substrate diffractions. By optimizing the grazing-incidence angle θ and adjusting the azimuthal angle φ, smooth extended X-ray absorption fine structure (EXAFS) oscillations were obtained for strained (La,Sr) 2 CuO 4 thin-film single crystals grown by molecular beam epitaxy. The results of EXAFS data analysis show that the local structure (CuO 6 octahedron) in (La,Sr) 2 CuO 4 thin films grown on LaSrAlO 4 and SrTiO 3 substrates is uniaxially distorted changing the tetragonality by ∼5 x 10 -3 in accordance with the crystallographic lattice mismatch. It is demonstrated that the local structure of thin-film single crystals can be probed with high accuracy at low temperature without interference from substrates.