Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Low-Dimensional Systems: Charge Order

TT 22.4: Vortrag

Montag, 31. März 2014, 15:45–16:00, BEY 81

Interplay of covalency and correlations in the edge shared spin 1/2 A₃T₂O₄ chain compounds (A = Na, K; T = Cu, Ni) — •Deepa Kasinathan¹, Klaus Koepernik², and Helge Rosner¹ — ¹MPI CPfS, Dresden, Germany — ²IFW Dresden, Germany

Na₃Cu₂O₄, K₃Cu₂O₄ and K₃Ni₂O₄ belong to a new class of quasi-1D insulating cuprates which feature strongly buckled, one-dimensional _∞¹CuO₂ ribbon-like chains consisting of edge-sharing CuO₄ plaquettes. Structural analysis of the metal-oxygen bond lengths and thermodynamic measurements[1,2,3] imply that these systems are intrinsically charge ordered (… (Ni/Cu)²⁺-(Ni/Cu)³⁺-(Ni/Cu)²⁺-(Ni/Cu)³⁺…) and show dominant antiferromagnetic interactions. No electronic structure analysis of these systems exist to date. Using density functional theory based calculations (LDA, Wannier functions, LDA+U), we analyze the microscopic origin of the magentic interactions in these systems. The main interaction along the chains are the second neighbor superexchanges. Nonetheless, a careful analysis of the first neighbor interaction between the mangnetic (Cu²⁺/Ni³⁺) cation and the non-magnetic cation (Cu³⁺/Ni²⁺) is necessary. We report on the interplay of covalency, crystal field splitting and correlations in these systems.
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