Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 10: Multiferroics II: Hexagonal manganites / Incommensurate multiferroics (jointly with MA, DF, KR, TT)

DS 10.5: Talk

Monday, March 26, 2012, 16:15–16:30, EB 301

Sinusoidal electromagnon in RMnO₃: Indication of anomalous magnetoelectric coupling — •Markku Stenberg¹ and Rogério de Sousa² — ¹Theoretical Physics, Saarland University, 66123 Saarbrücken, Germany — ²Department of Physics and Astronomy, University of Victoria, Victoria, B.C., V8W 3P6, Canada

The optical spectra in the family of multiferroic manganites RMnO₃ is a great puzzle. Current models can not explain the fact that two strong electromagnons are present in the non-collinear spin cycloidal phase, with only one electromagnon surviving the transition into the collinear spin sinusoidal phase. We show that this is a signature of the presence of anomalous magnetoelectric coupling that breaks rotational invariance in spin space and generates oscillatory polarization in the ground state.