Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.16: Poster

Dienstag, 23. März 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 (T_N = 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.