K. Yonemitsu et Ar. Bishop, INSTABILITY OF VORTEX TEXTURES IN THE 2-DIMENSIONAL HUBBARD-MODEL, Physical review. B, Condensed matter, 48(9), 1993, pp. 6680-6682
The Hubbard model on a two-dimensional square lattice is investigated
within an unrestricted, inhomogeneous Hartree-Fock approximation. Vort
exlike states discussed by Verges et al. [Phys. Rev. B 43, 6099 (1991)
] are studied in detail. They are found to be unstable against transve
rse spin fluctuations. Doping of holes does not suppress these fluctua
tions strongly enough to stabilize the vortex states.