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Zusammenfassung:
Modern theories of quantum magnetism predict exotic multipolar states in weakly interacting strongly frustrated spin-1/2 Heisenberg chains with ferromagnetic nearest neighbor (NN) inchain exchange in high magnetic fields. Experimentally these states remained elusive so far. Here we report strong indications of a magnetic field-induced nematic liquid arising above a field of similar to 13 T in the edge-sharing chain cuprate LiSbCuO4 = LiCuSbO4. This interpretation is based on the observation of a field induced spin-gap in the measurements of the Li-7 NMR spin relaxation rate T-1(-1) as well as a contrasting field-dependent power-law behavior of T-1(-1) vs. T and is further supported by static magnetization and ESR data. An underlying theoretical microscopic approach favoring a nematic scenario is based essentially on the NN XYZ exchange anisotropy within a model for frustrated spin-1/2 chains and is investigated by the DMRG technique. The employed exchange parameters are justified qualitatively by electronic structure calculations for LiCuSbO4.
