Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Quantum Magnets, Molecular Magnets and Skyrmions

TT 47.7: Vortrag

Mittwoch, 3. April 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 Janson³ — ¹MPI 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 δ_J1 ∼ 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.