  The Kotliar-Ruckenstein slave-boson scheme is used to allow for an
unrestricted variation of the bosonic and fermionic fields on the saddle-point
level. Various inhomogeneous solutions, such as spin polarons and domain walls
are discussed within the two-dimensional Hubbard model and compared with
results of unrestricted Hartree-Fock (HF) calculations. We find that the
present approach drastically reduces the polarization of these states and leads
to increased delocalized wave functions as compared to the HF model. The
interaction between two spin polarons turns out to be attractive over a wide
range of the on-site repulsion U. In addition we obtain the crossover from
vertical to diagonal domain walls at a higher value of U than predicted by HF.
