Effect of impurity potentials on antiferromagnetism in two-dimensional Hubbard model

Recent numerical studies have shown that antiferromagnetism (AF) prevails widely near half filling in the two-dimensional Hubbard (t-t′-U) model, contrary to the experiments on cuprate superconductors. In cuprates, disorders owing to the dopants, which are usually disregarded in theory, are possibly intrinsic and considerable. Thus, as a first step, we consider the effects of point-type impurity potentials, which are randomly distributed on the lattice sites, on the stability of AF. It is found that a moderate impurity potential does not modify the stability of AF, but a sufficiently strong attractive potential V(V ≲ -U) appreciably weakens an antiferromagnetic state owing to an insufficient screening of V.