Charge stripe order from antiphase spin spirals in the spin-Fermion   model
  We revisit the ground state of the spin-Fermion model within a semiclassical approximation. We demonstrate that antiphase spin spirals, or pi-spirals, whose chirality alternates between consecutive rows (or columns) of local moments, have, for sufficiently high carrier concentration, lower energy than the traditional Shraiman and Siggia spirals. Furthermore, pi-spirals give rise to modulated hopping, anisotropic 1D transport, and charge density wave formation. Finally, we discuss the relevance of pi-spirals to the physics of charge stripe formation in cuprates, such as La(2-x)Sr(x)CuO4. 
Marcello B. Silva Neto