  We investigate the paramagnetic-metal-to-antiferromagnetic-metal and
antiferromagnetic-metal-to- antiferromagnetic-insulator transitions using a
slave-boson mean-field theory. To this effect, we discuss the ground state of
the half-filled Hubbard model as a function of t'/t and correlation strength U,
where t and t' are the hopping amplitudes between nearest and next-nearest
neighbors, respectively. The metal-insulator transition at a critical U_{MIT}
is of second order for small levels of magnetic frustration, t'/t<0.06, and of
first order for large ones, t'/t>0.06. The insulator is always
antiferromagnetically ordered, while the metal exhibits a second-order
transition from a paramagnetic to an antiferromagnetic state up to t'/t=0.14,
as U is increased. We also contrast these findings with what we obtain in
Hartree-Fock approximation.
