Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.25: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Ultrafast optical spectroscopy of layered hole-doped manganites — •Lena Maerten, Marc Herzog, and Matias Bargheer — Institut für Physik und Astronomie, Universität Potsdam

Sr-doped perovskite oxide LaMnO₃ is widely studied for its ferromagnet to paramagnet and concomitant metal to insulator phase transition. Inserting a monolayer of SrO following each n unit cells of (LaSr)MnO₃ (Ruddlesden-Popper Series) introduces an intrinsic superlattice structure with strongly anisotropic properties such as a reduced dimensionality of the electron gas. Alternatively, artificial superlattices with dielectric oxides as interlayers can be prepared. Ultrafast optical spectroscopy reveals on which timescales the coupled electronic, lattice and spin degrees of freedom interact. Using IR pump / white-light probe and NOPA-based pump-probe techniques we measure transient reflectivity curves of bulk (n → ∞) and layered (n=2, n=3) SrO(La_0.65Sr_0.35MnO₃)_n for temperatures above and below the ferromagnetic transition. Fast electronic heating, consecutive electron-phonon coupling and a slow transfer of energy into the magnetic system can be observed. We discuss transient spectral changes and the build-up of zone-folded coherent acoustic phonons in the layered samples.