Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.48: Poster

Samstag, 5. März 2005, 11:00–16:30, Poster TU C

Electrostatically driven charge ordering in Fe₂OBO₃ — •I. Leonov¹, A. N. Yaresko², V. N. Antonov³, and V. I. Anisimov⁴ — ¹Theoretical Physics III, Institute for Physics, University of Augsburg — ²Max-Planck Institute for the Physics of Complex Systems, Dresden — ³Institute of Metal Physics, Vernadskii Street, 03142 Kiev, Ukraine — ⁴Institute of Metal Physics, Russian Academy of Science-Ural Division, 620219 Yekaterinburg GSP-170, Russia

Charge ordering in the low-temperature monoclinic structure of iron oxoborate (Fe₂OBO₃) is investigated using the local spin density approximation with Coulomb interaction correction (LSDA+U) method. While the difference between t_2g minority occupancies of Fe²⁺ and Fe³⁺ cations is large and gives direct evidence for charge ordering, the screening is so effective that the total 3d charge disproportion is rather small. The occupied Fe²⁺ and Fe³⁺ cations are ordered alternately within the chain which is infinite along a-direction, resulting in ferromagnetic intrachain order due to d⁵ − d⁶ superexchange. The charge order obtained by LSDA+U is consistent with observed enlargement of the β angle.