Excitation of an X-ray standing wave in a SmBa 2Cu 3O 7-δ thin film

An X-ray standing wave was generated by a 150 nm-thick SmBa ₂Cu ₃O _7-δ film grown on a SrTiO ₃(001) substrate by pulsed laser deposition. The Sm-L-fluorescence yield was measured as a function of incidence angle within the range of the (005) reflection from the thin film. The modulation of the yield indicated that for this particular epilayer the Sm is occupying the rare earth position (no occupation of Basites within the limit of error of ≈ 10%). Within the Bragg-reflection range, the modulation of the fluorescence yield is only a few percent. However, because the crystal is very thin, the reflection curve is rather wide (tenth of a degree) in angle. Employing brilliant synchrotron radiation this approach may be used routinely for structural studies of compound materials which are available as high-quality thin films but not as perfect single crystals.