Berlin 2018 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 8: Multiferroics and magnetoelectrics I (joint session MA/KFM)

KFM 8.1: Vortrag

Dienstag, 13. März 2018, 09:30–09:45, EB 202

Lu2Fe3O7 a quest for ferroelectricity by charge order — •Sabreen Hammouda and Manuel Angst — Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

Rare earth ferrites have attracted a lot of attention as proposed multiferroics. In particular, LuFe2O4 was considered a clear example of ferroelectricity from charge ordering (CO), though recently this was found not to be the case [1]. Structural modification, such as intercalation by LuFeO3, yielding Lu2Fe3O7 might render the bilayers polar. Furthermore, the only believable polarization hysteresis loop in the rare earth ferrite literature [2] was measured on an intercalated compound, slightly Mn-doped Lu2Fe3O7. A critical aspect of investigating these compounds is the oxygen-stoichiometry. We succeeded in growing single crystals of Lu2Fe3O7 using different CO2/CO gas mixtures to fine-tune the oxygen partial pressure. Single crystals examined by x-ray diffraction showed a short range ordering with a zigzagged diffuse scattering along (1/3 1/3 l), with positions similar to the observation by electron diffraction [3]. The diffuse nature indicates that the crystals are not quite stoichiometric enough for long range CO. Powder XRD measurements reveal a peak splitting which is likely due to structural distortion because of CO. Magnetic behavior of these crystals will also be discussed. As an outlook, further optimization is needed to determine the charge and spin structures. [1] de Groot et al., Phys. Rev. Lett. 108, 187601 (2012). [2] Qin et al., Appl. Phys. Lett. 95, 072901 (2009). [3] Yang et al., Phys. Status Solidi B 247, 870 (2010).