Regensburg 2010 – wissenschaftliches Programm
DS 8.11: Vortrag
Montag, 22. März 2010, 16:45–17:00, H3
Influence of Fe-substitution in LiNi(1−x)FexPO4 on the antiferromagnetic structure — •Elke Künzel1, Anne Zimmermann1, Jiying Li2, David Vaknin2, and Manfred Fiebig1 — 1HISKP, Universität Bonn — 2Ames Labatory and Department of Physics, Iowa States Univerity, Ames, USA
The LiMPO4 system (M=Fe, Ni, Co, Mn) includes crystallographically isostructural compounds with antiferromagnetic (AFM) order differing in the spin direction only. Thus, the system offers the opportunity to study fundamental mechanisms of AFM 180∘ domain formation in a range of similar but not identical compounds. In spite of their structural similarity, drastic differences in the domain topology are observed by optical SHG. Domains in LiNiPO4 form anisotropic platelets whereas in LiFePO4 they are isotropic and amoeba-like. It is yet unclear whether this surprising behaviour is due to the properties of the nickel ion or to the spin direction which points along z in LiNiPO4 and along y in LiFePO4.
In order to clarify this, samples with different mixing ratios of nickel and iron were studied. The domain structure of LiNiPO4 was found to become aboeba-like for an iron substitution of <<50%. An anomalous temperature dependence of the AFM order parameter and indications for a spin structure different from that of the end compounds was observed.
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