Regensburg 2022 – scientific programme

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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.16: Poster

Wednesday, September 7, 2022, 16:00–18:00, P3

Surface-Enhanced Raman Spectroscopy and Transient Reflectivity of Strained LSMO Thin Films — •Leonard Schüler, Tim Titze, Stefan Mathias, Daniel Steil, and Vasily Moshnyaga — I. Physikalisches Institut, Georg-August-Universität Göttingen

The effect of lattice strain on the structural and electronic surface reconstruction of epitaxial La_0.7Sr_0.3MnO₃/LaAlO₃ (LSMO/LAO) thin films has been studied by surface-enhanced optical measurements. Surface sensitivity is achieved by deposition of gold nanoparticles, in which the localized surface plasmon resonance enhances laser electric fields at the surface, enabling surface-enhanced Raman spectroscopy (SERS) and pump-probe reflectivity (SE-PPR) studies of the LSMO films. For this system, SERS reveals a structural surface reconstruction and signals an insulating surface state characterized by strong Jahn-Teller modes which are not present in the conventional Raman spectra of the ferromagnetic metallic LSMO/LAO films. Furthermore, a structural transition of the insulating surface is shown at T*=200-220 K possibly related to charge ordering (CO). SE-PPR indicates that it is possible to photoinduce a ferromagnetic metallic phase at the surface above the assumed CO transition temperature.