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MA: Magnetismus
MA 12: Quasiniedrigdimensionale Systeme
MA 12.2: Talk
Wednesday, March 13, 2002, 17:45–18:00, H22
Low temperature AFM ordering in the quantum Cu2+ (S=1/2) chain system, LiCuVO4 — •B. J. Gibson1, R. K. Kremer1, G. McIntyre2, A. V. Prokovief3, and W. Assmus3 — 1Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 2Institute Laue-Langevin, Grenoble, France — 3Physikalisches Institut der Universität Frankfurt a.M., Germany
LiCuVO4 crystallises as an orthorhombically distorted inverse spinel structure in which Cu2+ ions form linear chains along the b-axis. These linear chains are spaced by diamagnetic V-O tetrahedra and Li-O octahedra. Magnetic transitions are observed in χ and CP at T=27 K and at TN=2.5 K. Above TN the data can be well described by the Eggert-Affleck-Takahashi theory for S=1/2 uniform AFM Heisenberg chains.
In this contribution we will present our investigations on the magnetic ordering below TN=2.5 K by single crystal neutron diffraction at T≥0.3 K. We find an incommensurate magnetic structure, k=[0, 0.468, 0], with reduced Cu2+ moments confined to the ab-plane in a frustrated arrangement. The frustrated nature of the magnetic structure will be discussed on the basis of competing NN and NNN interactions anlong the chains, and the possibility of Dyzaloschinskii-Moriya interactions within this structure will be considered.