  The Hubbard model is studied in which disorder is introduced by putting the
on-site interaction to zero on a fraction f of (impurity) sites of a square
lattice. Using Quantum Monte Carlo methods and Dynamical Mean Field theory we
find that antiferromagnetic long-range order is initially enhanced at
half-filling and stabilized off half-filling by the disorder. The Mott-Hubbard
charge gap of the pure system is broken up into two pieces by the disorder: one
incompressible state remains at average density n=1 and another can be seen
slightly below n=1+f. Qualitative explanations are provided.
