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TT: Tiefe Temperaturen
TT 32: Correlated Electrons - Low-dimensional Materials II
TT 32.2: Talk
Tuesday, March 8, 2005, 16:30–16:45, TU H2053
Evidence for "ferromagnetic" helimagnetism in compounds with frustrated edge-shared CuO2 chains — •S.-L. Drechsler1, J. Richter2, J. Málek1, A. Moskvin3, H. Rosner4, A. Gippius5, R.E. Kremer6, and M. Enderle7 — 1IFW-Dresden — 2Universität Magdeburg — 3Ural State University Ekaterinburg, Russia — 4MPI f. CPfS, Dresden — 5State University, Moscow, Russia — 6MPI f. Festkörperforsch., Stuttgart — 7Inst. Laue-Langevin, Grenoble, France
We present a combined theoretical and experimental study of the electronic structure and helimagnetism in compounds with frustrated edge-shared CuO2 chains: LiVCuO4 and LiCu2O2 vs. the ferromagnetic (fm) inchain ordering in Li2CuO2. Based on full potential L(S)DA and LSDA+U band structure calculations, exact diagonalization studies of multi-band Hubbard and Heisenberg models, we estimate sign and magnitude of the most relevant exchange integrals J. Strongly competing fm nearest neighbor (nn) and anti-fm next nn J’s are found for the inchain direction. This frustration scenario well describes magnetic susceptibility, specific heat, spin entropy, inelastic neutron scattering, and NMR data. The influence of interchain couplings is briefly discussed.