Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 36: Poster Session I

DS 36.26: Poster

Thursday, March 19, 2015, 09:30–12:00, Poster A

Global and local Raman characterization of double perovskite thin films — •Hendrik Ehlers, Christoph Meyer, Florian Fischgrabe, Vasily Moshnyaga, Bernd Damaschke, and Konrad Samwer — I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

B-site ordered double perovskites La₂CoMnO₆ (LCMO) and Pr₂CoMnO₆ (PCMO) with monoclinic P12₁/n₁ structure can be derived from a single perovskite by alternating layers of Co²⁺ and Mn⁴⁺ on the B-site. They are promising for spintronic applications due to ferromagnetic ordering, spin-phonon and magnetodielectric coupling. Since the properties are strongly influenced by the type of the rare earth A-cation and by the degree of the ordering, we used Raman spectroscopy as a global and local tool to correlate the phonon spectra with B-site ordering and A-cation influence. Therefore far-field Raman and tip-enhanced Raman spectroscopy (TERS) of LCMO and PCMO thin films on SrTiO₃(100) and SrTiO₃(111) substrates, grown by metalorganic aerosol deposition (MAD), was performed. The spectra exhibit a strong A_g mode in the 600−700 cm⁻¹ range, indicating B-site cation ordering. Applying TERS, the spectra reveal anenhancement in a parallel as well as in the cross-scattering configuration due to a combination of field enhancement and depolarization effects. Additionally we present first TERS results on single perovskite CaMnO₃ thin films with intensity enhancement and an emergence of a new phonon mode at 650 cm⁻¹.Financial support for this work by the DFG via project SFB 1073/B04 is gratefully acknowledged.