Regensburg 2013 – wissenschaftliches Programm

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KR: Fachgruppe Kristallographie

KR 1: Multiferroics 1 (MA jointly with DF, DS, KR, TT)

KR 1.3: Vortrag

Montag, 11. März 2013, 10:00–10:15, H3

Investigation of magnetic ordering in Eu_1−xY_xMnO₃ using full polarization analysis at P09 beamline — •Arvid Skaugen, Dinesh K. Shukla, Helen Walker, Sonia Francoual, and Jörg Strempfer — Deutsches Elektronen-Synchrotron, Harmburg, Germany

Varying multiferroic properties with strong ME coupling have been reported for Eu_1−xY_xMnO₃ [1]. The crystal structure of Eu_1−xY_xMnO₃ is similar to the one of TbMnO₃ with comparable lattice distortions. However, the effect of rare earth magnetism is eliminated since Eu³⁺ (4f⁶) and Y³⁺ (4f⁰) ions both are non-magnetic. The compound Eu_0.8Y_0.2MnO₃ first shows a phase transition at T_N = 45K from a paramagnetic to an antiferromagnetic and paraelectric state with a presumably sinusoidal collinear AFM structure, in analogy to TbMnO₃. At T_C = 30K the magnetic structure changes to weak ferromagnetism, attributed to a cone-like structure that breaks inversion symmetry and gives rise to ferroelectricity with the polarization along the a-axis.

We have investigated Eu_0.8Y_0.2MnO₃ using resonant x-ray diffraction as function of temperature, magnetic field and incident polarization at beamline P09 at PETRA III. The method of full polarization analysis has been used to investigate the different resonances showing up at the Mn K-edge. From the polarization scans, it is possible to draw conclusions on the complex magnetic order. Preliminary results suggest a helicoidal SDW structure of the Mn moments rather than a cone-like structure.

[1] J. Hemberger et al., Phys. Rev. B 75, 035118 (2007)