Regensburg 2010 – scientific programme
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MA: Fachverband Magnetismus
MA 10: Poster I
MA 10.19: Poster
Tuesday, March 23, 2010, 10:45–13:45, Poster A
Influence of doping on the lattice dynamics: Comparison of stoichiometric and mixed orthorhombic rare earth manganites RMnO3 (R = Gd, Tb, Eu:Y) — •S. Issing1, F. Fuchs1, C. Ziereis1, E. Batke1, A. Pimenov1, Y. Vu. Ivanov2, A. A. Mukhin2, and J. Geurts1 — 1Physikalisches Institut, Universität Würzburg, Germany — 2General Physics Institute of the Russian Academy of Sciences, Moscow, Russia
Among the class of multiferroics, the orthorhombic manganites RMnO3 are an excellent example for the intimate coupling of lattice and magnetic degrees of freedom. For a fine tuning of the magnetic properties the isovalent substitution of the R ion can be employed leading to a quasi-continuous increase of the orthorhombic crystalline distortion and thus of the magnetic frustration responsible for multiferroicity. However the question of disorder induced by isovalent substitution needs to be adressed. Thus, employing Raman and FTIR spectroscopy, we studied the lattice dynamics of stoichiometric (R = Eu, Gd, Tb) as well as mixed RMnO3 compounds (Eu1−xYx 0≤x≤0.5 - covering the R ion radius from Eu to Tb) - to gain insight into the consequences of an isovalent partial substitution on the R-site. Our spectroscopic techniques give us sensitivity not only to symmetry properties but also to the involvement of different ion types within the unit cell. Our results clearly show that the MnO6-octahedra remain unaffected by disorder, making Eu1−xYxMnO3 an excellent model system for a quasi-continuous fine-tuning of the lattice properties relevant for the appearance of multiferroicity.
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