  We study the Kondo Lattice Model (KLM) on a square lattice through a
Hartree-Fock approximation in which the local spins are treated
semi-classically, in the sense that their average values are modulated by a
magnetic wavevector $\mathbf{Q}$ while they couple with the conduction
electrons through fermion operators. In this way, we obtain a ground state
phase diagram in which spiral magnetic phases (in which the wavevector depends
on the coupling constants and on the density) interpolate between the
low-density ferromagnetic phase and the antiferromagnetic phase at half
filling; within small regions of the phase diagram commensurate magnetic phases
can coexist with Kondo screening. We have also obtained `Doniach-like'
diagrams, showing the effect of temperature on the ground state phases, and
established that for some ranges of the model parameters (the exchange coupling
and conduction electron density) the magnetic wavevector changes with
temperature, either continuously or abruptly (e.g., from spiral to
ferromagnetic).
