Phases of the 2D Hubbard model at low doping
  We show that the planar spiral phase of the 2D Hubbard model at low doping, x, is unstable towards a noncoplanar spin configuration. The novel equilibrium state we found at low doping is incommensurate with the inverse pitch of the spiral varying as x^(1/2), but nevertheless has a dominant peak in the susceptibility at (\pi,\pi). Relevance to the NMR and neutron scattering experiments in La_2-xSr_xCuO_4 is disccussed. 
A.V.Chubukov and K.A.Musaelian