Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.14: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Raman spectroscopy on thin manganite films — •Sebastian Merten¹, Sebastian Hühn¹, Antje Krüger¹, Christin Kalkert¹, Burkhard Schmidt², and Vasily Moshnyaga¹ — ¹I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Abteilung Mineralogie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, Goldschmidtstraße 1, 37077 Göttingen, Germany

A commonly believed picture is the colossal magnetoresistance effect in thin manganite films is related to a first order magnetic phase transition which can be also coupled to a structural phase transition from an orthorhombic (Pnma) to a rhombohedral (R3c) structure. This structural change can be reflected in Raman spectra which provide information of the phonon modes specific to the structural phases involved. Here we report on the Raman spectroscopy of epitaxial manganite films of La_0.7Sr_0.3MnO₃, La_0.7Ca_0.3MnO₃ and (La₆₅Pr₄₅)_0.7Ca_0.3MnO₃ grown on MgO (100)-substrates. We observed the known Raman peaks characteristic for both structures as was identified in previous works. Moreover, the details of the phase transition and phase competition could be obtained from the temperature behaviour of the Raman peaks. In addition first results of Surface-enhanced Raman spectroscopy (SERS) will be presented on La_0.7Ca_0.3MnO₃. We covered the surface of the films with commercially available gold nanoparticles with the dimensions of 25x60 nm and detected an enhancement of 2-3 orders of magnitude. SFB 602(TPA2) is acknowledged.