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Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 47: Quantum Magnets, Molecular Magnets and Skyrmions

TT 47.7: Talk

Wednesday, April 3, 2019, 16:30–16:45, H23

Strong influence of ’bystanders’ on the exchange in edge-shared Cu-O chain compounds — •Helge Rosner1, Dijana Milosavljevic1, Jan Tomczak2, Stefan-Ludwig Drechsler3, and Oleg Janson31MPI CPfS Dresden, Germany — 2TU Wien, Austria — 3IFW Dresden, Germany

The influence of the structural features like bond angles and distances on the exchange integrals in cuprate materials has been studied in detail for many years. One of the dominating structural features is the Cu-O-Cu bond angle in chain-like compounds. However, similarly strong influence on the exchange couplings by side groups was observed recently. As an example, we analyse the origin of the huge difference δJ1 ∼ 200 K for the nearest neighbour exchange in Li2CuO2 and SiCuO3, which have structurally nearly identical CuO2 chains. For closely related materials, we also demonstrate the strong influence of hydrogen positions in the crystal structure for O-H groups or crystal water on the leading exchange terms, changing from strongly antiferromagnetic to moderately ferromagnetic. We elucidate the underlying microscopic mechanisms based on detailed DFT studies and subsequently derived multi-band tight-binding models. The results widely improve our understanding of magneto-structural correlations in cuprate compounds.

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