High field magnetization of the frustrated one-dimensional quantum antiferromagnet LiCuVO4

We have investigated the high field magnetization of the frustrated one-dimensional compound LiCuVO4. In zero field, LiCuVO4 undergoes long range antiferromagnetic order at T-N approximate to 2.5 K with a broad short range Schottky type anomaly due to one- dimensional correlations in the specific heat at 32 K. Application of a magnetic field induces a rich phase diagram. An anomaly in the derivative of the magnetization with respect to the applied magnetic field is seen at similar to 7.5 T with H parallel to c in the long range order phase. We investigated this in terms of a first experimental evidence of a middle field cusp singularity ( MFCS). Our numerical density matrix renormalization group results show that in the parameter range of LiCuVO4 as deduced by inelastic neutron scattering ( INS), there exists no MFCS. The anomaly in the derivative of themagnetization at similar to 7.5 T is therefore assigned to a change in the spin structure from the ab plane helix seen in zero field neutron diffraction.