Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 2: Thin Film Characterisation I: Structure Analysis and Composition

DS 2.1: Talk

Monday, March 16, 2015, 09:30–09:45, H 0111

Probing the oxygen deficit in YBCO thin films with a positron beam — •Markus Reiner¹, Thomas Gigl¹, Rainer Jany², German Hammerl², and Christoph Hugenschmidt¹ — ¹Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department E21, Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany — ²Experimentalphysik VI, Elektronische Korrelationen und Magnetismus, Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany

High quality single-crystalline YBa₂Cu₃O_7−δ (YBCO) thin films were grown epitaxially by pulsed laser deposition. After tempering under different conditions they were characterized by various techniques such as electrical conductivity measurements, X-ray diffraction and electron microscopy. The highly intense reactor based positron beam NEPOMUC was applied for Doppler Broadening Spectroscopy (DBS). A strong correlation between the Doppler broadening of the positron annihilation line and the oxygen deficit was found and its origin was examined by ab-initio calculations. This correlation enabled the study of the kinetics of oxygen out diffusion from the YBCO thin film during in-situ measurements at temperatures up to 673 K. Furthermore, the high spatial resolution of the positron beam (up to around 0.3 mm) was used for mapping the oxygen deficit and hence, to probe the spatial homogeneity of the oxygen distribution in the examined YBCO films. Financial support within the Project No. 05KI0WOB by the BMBF is gratefully acknowledged.