  The slave-particle representation is a promising method to treat the
properties of exotic strongly correlated systems. We develop a unified approach
to describe both the paramagnetic state with possible spin-liquid features and
states with strong long-range or short-range magnetic order. Combining the
Kotliar-Ruckenstein representation and fractionalized spin-liquid deconfinement
picture, the Mott transition and Hubbard subbands are considered. The spectrum
in the insulating state is significantly affected by the presence of the spinon
spin-liquid spectrum and a hidden Fermi surface. Presenting a modification of
the Kotliar-Ruckenstein representation in the spin-wave region, we treat the
case of magnetic order, with special attention being paid to the half-metallic
ferromagnetic state. The formation of small and large Fermi surfaces for doped
current carriers in the antiferromagnetic state is also discussed.
