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Magnetismus Poster: Do., 13:00–15:30 D-P216
Possible evidence for weak charge ordering near half doping in Na0.46CoO2
D. Argyriou 1 , O. Prokhnenko 1 , K. Kiefer 1 , C. Milne 2
1 Hahn-Meitner-Institut, Glienicker Str. 100, Berlin D-14109, Germany
We have utilized neutron powder diffraction to probe the crystal structure of layered
NaxCoO2 near the half doping composition of x =0.46. Our measurements show evidence
of weak charge separation into stripes of Co +3.5+ɛ and Co +3.5−ɛ , ɛ ∼0.06e below
T ′ =150 K, pointing to the development of a weak charge density wave (CDW) that
locks − in at a lower temperature. The pattern of charge ordering reflects the Na-ion
potential which leads to a distortion of CoO6 octahedra depending on the CoO6-Na
coordination.