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DS: Fachverband Dünne Schichten

DS 6: Thin Film Characterization: Structure Analysis and Composition (XRD, TEM, XPS, SIMS, RBS,...)

DS 6.18: Talk

Monday, March 31, 2014, 19:45–20:00, CHE 89

Resonant X-ray reflectometry study of YBa₂Cu₃O_7−δ thin films: An atomic approach to reflectivity — •Jorge E. Hamann-Borrero¹, Sven Partzsch¹, Benjamin Gray², Sebastian Macke³, Enrico Schierle⁴, Martin Zwiebler¹, John W. Freeland⁵, Jak Chakhalian², Bernd Buechner¹, and Jochen Geck¹ — ¹IFW-Dresden — ²Department of Physics University of Arkansas, USA — ³Max Planck-UBC Centre for Quantum Materials, Vancouver, Canada — ⁴Helmholtz-Zentrum Berlin für Materialien und Energie — ⁵Advanced Photon Source, Argonne National Laboratory, Illinois, USA

We present a Cu L_2,3 Resonant X-ray Reflectometry study of a (001)-YBCO thin film grown on SrTiO₃. The reflectivities measured using σ and π polarized light show a strong dichroism due to the local anisotropy of the different copper sites at the plane and chain layers of this compound. Within the scanned q-range also the (001) Bragg reflection appears highlighting the importance of the interference between the different scattering centers in the sample.

In order to describe the observed intensities, traditional models such as the Parrat’s formalism fail, since they neglect the interference between the atomic scatterers. Therefore, we employed a new atomistic approach to model reflectivity where the most important structural, finite size, surface and interface effects, are considered by explicitly defining the atom positions together with their anisotropic scattering form factors. First calculations will be presented and discussed.