  The magnetic phase diagram of slightly overdoped La{2-x}Sr{x}CuO{4} (x=0.17)
is characterised by a field-induced hexagonal to square transition of the
vortex lattice at low fields (~0.4 Tesla) [R. Gilardi et al., Phys. Rev. Lett.
88, 217003 (2002)]. Here we report on a small angle neutron scattering study of
the vortex lattice at higher fields, that reveals no further change of the
coordination of the square vortex lattice up to 10.5 Tesla applied
perpendicular to the CuO2 planes. Moreover, it is found that the diffraction
signal disappears at temperatures well below Tc, due to the melting of the
vortex lattice.
