  We address the possibility of spiral ferrimagnetic phases in the mean-field
phase diagram of the two-dimensional (2D) Hubbard model. For intermediate
values of the interaction $U$ ($6 \lesssim U/t \lesssim 11$) and doping $n$, a
spiral ferrimagnetic phase is the most stable phase in the $(n,U)$ phase
diagram. Higher values of $U$ lead to a non-spiral ferrimagnetic phase. If
phase separation is allowed and the chemical potential $\mu$ replaces the
doping $n$ as the independent variable, the $(\mu,U)$ phase diagram displays,
in a considerable region, a spiral (for $6 \lesssim U/t \lesssim 11$) and
non-spiral (for higher values of $U$) ferrimagnetic phase with fixed particle
density, $n=0.5$, reflecting the opening of an energy gap in the mean-field
quasi-particle bands.
