Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.32: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

Distinction of the SrTiO₃/NdGaO₃ surface termination by phase resolved Second Harmonic Generation — •Thomas Fink¹, Andrea Rubano¹, Tim Günter¹, Domenico Paparo², Carmela Aruta², Fabio Miletto Granozio², Umberto Scotti Di Uccio², Lorenzo Marrucci², and Manfred Fiebig¹ — ¹HISKP, University of Bonn, Germany — ²CNR-INFM Coherentia, Università Frederico II, Napoli, Italy

The development of new oxide heterostructures, like LaAlO₃/SrTiO₃, requires to control the substrate surface termination. Under normal conditions, a TiO₂ termination of SrTiO₃ is favored. However, recent experiments demonstrated that a SrO termination can be achieved by epitaxially growing the SrTiO₃ on a NdGaO₃ substrate.

Second Harmonic Generation (SHG) is an ideal tool for studying surface phenomena, since it is sensitive to surface-induced symmetry breaking. Furthermore, it allows to directly image the sample surface. Here, we report on SHG imaging of the SrTiO₃ /NdGaO₃ surface using amplified femtosecond laser pulses. For 24 unit cells of SrTiO₃ epitaxially grown on NdGaO₃, two distinct types of domains with a length scale of about 500 µ m, are observed. By interference with a reference signal, we measured a 180^∘ SHG phase shift and an additional intensity difference between both of them. The phase shift can be directly assigned to the termination of SrTiO₃. Thus, phase-resolved SHG is an ideal tool in order to distinct different surface terminations, opening new possibilities to control the oxide interface electronic property.