Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: CE: Spin Systems and Itinerant Magnets

TT 22.12: Vortrag

Mittwoch, 24. März 2010, 12:30–12:45, H21

Low-dimensional magnetic properties of anhydrous (black) dioptase. — •J. M. Law¹, C. Hoch¹, M.-H. Whangbo², and R. K. Kremer¹ — ¹Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — ²Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, U.S.A.

Hydrous dioptase, CuSiO₃·H₂O is a low-dimensional quantum antiferromagnet. From a theoretical and experimental investigation it was proposed that hydrous dioptase is close to a quantum critical point.[1] Anhydrous dioptase, CuSiO₃ has a very similar magnetic lattice. We carried out a single-crystal structure determination and investigated the magnetic properties of anhydrous dioptase by carrying out specific heat and magnetic susceptibility measurements and performed a spin dimer analysis based on extended Hückel tight-binding calculations. We found that anhydrous dioptase conforms very well to a S=1/2 antiferromagnetic quantum chain model with uniform nearest-neighbor exchange interaction. Intra-chain interaction is by two orders of magnitude smaller than inter-chain superexchange and leads to long-range antiferromagnetic ordering at about 5 K.

[1] C. Gros et al.,Europhys. Lett. 2002, 60, 276.