Regensburg 2010 – scientific programme
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MA: Fachverband Magnetismus
MA 10: Poster I
MA 10.16: Poster
Tuesday, March 23, 2010, 10:45–13:45, Poster A
Investigation of strain effects in epitaxial CaMnO3 films by nonlinear optics — •Tim Günter1, Satadeep Bhattacharjee2, Philippe Ghosez2, Adrian David3, Wilfrid Prellier3, and Manfred Fiebig1 — 1HISKP, University of Bonn, Germany — 2University of Liege, Belgium — 3CRISMAT Laboratory, ENSICAEN, CNRS, France
The family of ABO3 perovskite oxide compounds constitutes an important class of multifunctional materials. For CaMnO3, a G-type antiferromagnetic insulator (TN = 122 K), a weak Mn-driven ferroelectric instability at its equilibrium volume was recently predicted. Furthermore this instability can be enhanced by strain engineering, driving CaMnO3 towards multiferroicity.
Here optical second harmonic generation (SHG) was used for investigating CaMnO3 films grown epitaxially with 2% tensile strain on (001)-LaAlO3 substrates. The temperature dependence of the SHG signal indicates a phase transition at ≈ 20 K with an emergence of long range order that is not found in the bulk compound. SHG polarization analysis based on SHG selection rules allows to determine the origin of this novel phase. A variety of possible ferroelectric polarization directions was considered on the basis of a symmetry analysis. First results on SHG spectroscopy and domain imaging are reported.
This work is supported by the EU-STREP MaCoMuFi.
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