Holes and magnetic textures in the two-dimensional Hubbard model

The Hubbard model in a two-dimensional square lattice is studied within the unrestricted Hartree-Fock approximation. It is shown that a large number of self-consistent solutions exist, which correspond to possible metastable spin and charge configurations. A solution, in which the spins are coplanar and form a vortexlike pattern, is described. The solution is stable over most of the parameter range and dominates for large values of U/t or at high doping. The influence of this multiplicity of solutions on the phase diagram is discussed.