  In this paper we present for the first time the exact solution in the
narrow-band limit of the 1D extended Hubbard model with nearest-neighbour
spin-spin interactions described by an exchange constant J. An external
magnetic field h is also taken into account. This result has been obtained in
the framework of the Green's functions formalism, using the Composite Operator
Method. By means of this theoretical background, we have studied some relevant
features such as double occupancy, magnetization, spin-spin and charge-charge
correlation functions and derived a phase diagram for both ferro (J>0) and
anti-ferro (J<0) coupling in the limit of zero temperature. We also report a
study on density of states, specific heat, charge and spin susceptibilities. In
the limit of zero temperature, we show that the model exhibits a very rich
phase diagram characterized by different magnetic orders and by the coexistence
of charge and spin orderings at commensurate filling. Moreover, our analysis at
finite temperature of density of states and response functions shows the
presence of low-temperature charge and spin excitations near the phase
boundaries.
