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The new magnetic phase of recently found by specific heat measurements has been investigated by means of neutron diffraction. This new phase is found very close to the critical temperature and it widens to a few tenths of a degree Kelvin in very high magnetic fields. The availability of a new strong steady-state magnet with a nominal strength of 14.5 T provided us with the opportunity to investigate the magnetic structure. We found that the new phase is also incommensurate, but that it no longer has the triangular antiferromagnetic structure. A proposal for the structure derived from a Landau theory put forward in the following theory paper by Jacobs and Nikuni is compared to the experimental results. The order of the transitions observed will be discussed, as well as our failure to observe a predicted commensurate phase.

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