Berlin 2015 – wissenschaftliches Programm

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KR: Fachgruppe Kristallographie

KR 3: Poster Session on Ferroic Domain Walls - Multiferroics (DF jointly with KR, MA, TT)

KR 3.22: Poster

Montag, 16. März 2015, 19:00–21:00, Poster C

X-ray diffraction on stoichiometric YFe₂O₄ single crystals. — •Thomas Müller and Manuel Angst — Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

LuFe₂O_4−δ was long considered to be the primary example for a charge order multiferroic. YFe₂O_4−δ is isostructural, but the ionic radius of Y is much larger compared to Lu, leading to completely different ordering phenomena. We have grown highly stoichiometric single crystals of YFe₂O_4−δ by the optical floating zone method, showing for the first time 3D charge ordering in x-ray diffraction at low temperature. The phase at 200 K can be indexed using a propagation vector of (1/7 1/7 9/7) considering 6 twin components and second order. Likewise the 160 K phase can be index with q=(1/4 1/4 3/4). While cooling not only the threefold symmetry but in contrast to LuFe₂O₄ also the mirror plane of the room temperature R3m structure of YFe₂O_4−δ are lost according to symmetry-analysis.