  We analyze the repulsive fermionic Hubbard model on square and cubic lattices
with spin imbalance and in the presence of a parabolic confinement. We analyze
the magnetic structure as a function of the repulsive interaction strength and
polarization. In the first part of the paper we perform unrestricted
Hartree-Fock calculations for the 2D case and find that above a critical
interaction strength $U_c$ the system turns ferromagnetic at the edge of the
trap, in agreement with the ferromagnetic Stoner instability of a homogeneous
system away from half-filling. For $U<U_c$ we find a canted antiferromagnetic
structure in the Mott region in the center and a partially polarized
compressible edge. The antiferromagnetic order in the Mott plateau is
perpendicular to the direction of the imbalance. In this regime the same
qualitative behavior is expected for 2D and 3D systems. In the second part of
the paper we give a general discussion of magnetic structures above $U_c$. We
argue that spin conservation leads to nontrivial textures, both in the
ferromagnetic polarization at the edge and for the Neel order in the Mott
plateau. We discuss differences in magnetic structures for 2D and 3D cases.
