Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”

TT 24.53: Poster

Mittwoch, 10. März 2004, 14:30–19:00, Poster A

Magnetic and orbital correlations in single layered manganates — •D. Senff¹, O. Friedt¹, M. Ben Omar¹, Y. Sidis², P. Reutler^3,4, A. Revcolevschi⁴, and M. Braden¹ — ¹II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln — ²Laboratoire Léon Brillouin,CE-Saclay, F-91191 Gif-sur-Yvette — ³IfW Dresden, Helmholtzstr. 20, D-01069 Dresden — ⁴Laboratoire de Physico-Chimie de l’Etat Solide, Université Paris Sud, F-91405 Orsay Cedex

We have studied the magnetic and charge/orbital order in La_1−xSr_1+xMnO₄ by elastic and inelastic neutron scattering. The antiferromagnetic transition and the spinwave dispersion of the parent compound LaSrMnO₄ show a typical 2D behavior. There is a large anisotropy gap of 9meV, but we find additional localized magnetic scattering below this spin-wave gap whose intensities increase upon minor Sr-content enhancement. For higher Sr-concentrations, x>0.4, the system exhibits at low temperatures charge-orbital ordering, best established for the concentration of x=0.5. In La_0.4Sr_1.6MnO₄ (x=0.6) we find incommensurate ordering most likely induced by the additional number of Mn⁴⁺-ions. The resulting orbital and magnetic structure may be interpreted in a stripe picture similar to the nickelates.

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