  We have investigated the high field magnetisation of the frustrated one
dimensional compound LiCuVO4. In zero field, LiCuVO4 undergoes long range
antiferromagnetic order at T_{N} ~ 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 magnetisation with respect to the applied magnetic field is
seen at ~ 7.5 T with H ll 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 DMRG 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 the magnetisation at ~ 7.5 T is therfore assigned
to a change in the spin structure from the ab plane helix seen in zero field
neutron diffraction.
