Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 12: Kondo / Heavy Fermions
MA 12.1: Vortrag
Montag, 27. März 2006, 16:30–16:45, HSZ 403
Magnetic ground state of the frustrated one dimensional binary compound CuCl2 — •Michael Banks1, Reinhard K Kremer1, and Bachir Ouladdiaf2 — 1MPI-FKF, 70569 Stuttgart — 2ILL Grenoble, CEDEX 9
Historically, the binary CuCl2 and the structurally similar CuBr2 are among the very first systems the magnetic properties of which were analyzed in terms of a linear spin chain arrangements. Low-dimensional magnetism with typical signatures, e.g. a broad short-range ordering maxima in the susceptibility and heat capacity, have been found. The antiferromagnetic (afm) intra-chain exchange parameters are significant (e.g. ≈320K for CuBr2). However, both systems are far from representing ideal one-dimensional magnets as must be concluded from the rather high transition temperatures to long-range ordering (e.g. 24 K for CuCl2) indicating appreciable inter-chain coupling. To the best of our knowledge, the magnetic structures of CuCl2 and CuBr2 remain unsolved until now. We studied the afm ordering of CuCl2 and CuBr2 in detail by neutron powder diffraction using ILL’s high flux powder diffractometer D20 in its high resolution option. Using single crystals of CuCl2, we used the 4-circle diffractometer D10 also at the ILL to conclusively solve the magnetic structure. The magnetic structure of CuCl2 will be presented as showing helicoidal ordering along the chain direction with an incommensurate propagation vector τ = [0.5,0.224,0]. The magnetic phase diagram will be presented showing a spin-flop phase along the chain direction at HSF ≈ 4T.