Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 29: Spin Structures / Magnetic Phase Transitions
MA 29.2: Vortrag
Donnerstag, 28. Februar 2008, 18:00–18:15, H 1012
Magnetic Structure of GdMnO3 — •Anne Möchel1, Jörg Voigt1, Martin Meven2, Jong-Woo Kim3, and Thomas Brückel1 — 1Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — 2Technische Universität München, ZWE FRM II, 85748 Garching, Germany — 3Ames Laboratory, Ames, Iowa 50011, USA
We present the results of a combined neutron diffraction and X-ray resonance exchange scattering study of a GdMnO3 single crystal carried out in order to clarify the magnetic structure. Below the Néel-Temperature TN=41.6K, we find an incommensurate structure with a spin polarisation aligned parallel to the c-direction. At low temperatures (T≈15K) we have a step-like change of the propagation vector τ to an near commensurate τ=0.245 associated with a strong increase in intensity.
The onset of magnetic order is reflected by a λ anomaly in the specific heat, which shows no anomaly at 15K, where the propagation vector shows the sudden change. The magnetic susceptibility reveals a reduced paramagnetic effective moment as compared to the moments expected for free Gd3+ and Mn3+. A possible model for the magnetic structure is proposed based on the above observations.