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TT: Fachverband Tiefe Temperaturen

TT 35: CE: Low-dimensional Systems - Materials 3

TT 35.10: Vortrag

Mittwoch, 16. März 2011, 16:30–16:45, HSZ 301

Imaging of the two-dimensional polarization landscape at the LaAlO₃/SrTiO₃ interface — •Tim Günter¹, Andrea Rubano¹, Thomas Fink¹, Domenico Paparo², Fabio Miletto Granozio², Umberto Scotti di Uccio², Lorenzo Marrucci², Jochen Mannhart³, and Manfred Fiebig¹ — ¹HISKP, University of Bonn, Germany — ²CNR-INFM Coherentia, Università Federico II, Napoli, Italy — ³Center for Electronic Correlations and Magnetism, University of Augsburg, Germany

LaAlO₃/SrTiO₃ interfaces are a challenging topic in the field of perovskite oxides. A conductive two-dimensional electron liquid (2DEL) appears at the interface for a LaAlO₃ thickness of n≥4 unit cells. However, many questions regarding the origin and characteristics of the 2 DEL have to be adressed yet. In particular, this includes the spatial homogeneity of the interface reconstruction.

Second Harmonic Generation (SHG) is an ideal tool for studying interfaces, since it is sensitive to the interfacial symmetry breaking along the stacking direction. Furthermore, the spatial degrees of freedom of optical techniques can be exploited. Here we use SHG with amplified femtosecond laser pulses for imaging the LaAlO₃/SrTiO₃ interface with a spatial resolution of ≈ 2 µm. For n=1 a pronounced interfacial inhomogeneity on a lengthscale of < 1 µm is observed. The lateral dimension of these inhomogeneities increases for n=2 pointing to a step-like reconstruction of the interface. At n=3, the interface becomes homogeneous which may reflect the completion of a fully reconstructed interface, though yet without the emergence of conductivity.