Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 23: Soft and hard permanent bulk magnets
MA 23.7: Vortrag
Dienstag, 2. April 2019, 15:30–15:45, H53
Low-Dimensional Magnetic Properties of Natural and Synthetic Mixite (Bi,Ca)Cu6(OH)6(AsO4)3 * nH2O (n 3) and Goudeyite YCu6(OH)6(AsO4)3 * nH2O (n 3) — •Aleksandr Golubev1, Eva Brücher1, Armin Schulz1, Reinhard Kremer1, Franz Schmidt2, Elija Gordon3, and Myung-Hwan Whangbo3 — 1Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 2Staatliches Museum für Naturkunde, Stuttgart, Germany — 3North Carolina State University, Raleigh. USA
The minerals mixite and goudeyite with composition (Bi,Ca)Cu6(OH)6(AsO4)3*nH2O(n = 3) and YCu6(OH)6(AsO4)3*nH2O (n = 3) crystallize in the space group P 63/m (no. 176) with a "zeolite-type" channel structure with a honeycomb arrangement of rings composed of six CuO4 ribbon chains. The structural, vibrational and magnetic properties of natural and synthetic polycrystalline samples of the minerals mixite and goudeyite have been investigated. The magnetic susceptibilities are characterized by low-dimensional antiferromagnetic short range ordering and can be described as spin S=1/2 alternating Heisenberg chain with nearest-neighbor spin exchange ranging between 200 K and 130 K for natural mixite and synthetic goudeyite, respectively. The alternation parameters range between 0.52 for natural mixite and 0.75 for synthetic mixite and goudeyite, respectively. The experimentally observed spin exchange parameters are consistent with DFT calculations of the spin exchange parameters.