Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 20: Multiferroics

MA 20.10: Talk

Wednesday, February 27, 2008, 16:30–16:45, EB 202

Nonlinear optics on multiferroic tricolor superlattices — •Thomas Lottermoser^1,2, Hiroyuki Yamada³, Jobu Matsuno², Takahisa Arima^2,4, Masashi Kawasaki^3,5, Manfred Fiebig¹, and Yoshinori Tokura^2,3,6 — ¹HISKP, Universität Bonn, 53115 Bonn, Germany — ²ERATO, Multiferroics Project, JST, Tokyo 113-8656, Japan — ³CERC, AIST, Tsukuba 305-8562, Japan — ⁴IMRAM, Tohoku University, Sendai 980-8577, Japan — ⁵Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan — ⁶Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan

While multiferroics propose new physical phenomena and technical applications, materials exhibiting pronounced magnetoelectric coupling are still rare. Here, a new concept based on tricolor superlattices composed of repeated sequences of the transition-metal oxides SrMnO₃, LaMnO₃ and LaAlO₃ is used. Electron transfer at the interfaces of the antiferromagetic insulators SrMnO₃ and LaMnO₃ leads to a modification of their magnetic and electronic behavior. The electronic state near the interface is modified to be a ferromagnetic metal like (La, Sr)MnO₃. In addition, the charge transfer produces electric dipole moments along the stacking direction that do not cancel out in the ABCABC stack. Therefor the tricolor superlattices are polar ferromagnets. The artificial symmetry breaking allows (non-)magnetic contributions to optical second harmonic generation (SHG) which we used to probe directly the magnetic properties of the superlattice interfaces. The dependence on layer thickness and stress induced by different kinds of substrates is reported.