Site order parameter p_g in ±J Ising square lattices

Ising lattices with ±J exchange interactions present frustration that raises the energy of the ground level as well as its degeneracy. This leads to think that after going over the states in half the configuration space, the different ground states will end up alternating all spins yielding a null site order parameter. In the present work we give numerical results that indicate that there is always a large region in these lattices, which remains free of frustration in the ground state. So if the ergodic separation is done in such a way as lo leave this region with one possible spin orientation on one half the configuration space and the other spin orientation in the other half, it is possible to define a partial spin-glass phase with a positive site order parameter.