Intermediate spin-charge order in the cuprates

On the basis of a rigorous constraint we show that the doped cuprates either exhibit electronic phase-separation, or balance right at the phase-separation threshold. We suggest that the pseudo-gap phase can be identified with the state that is nano-scale phase-separated in magnetic and non-magnetic phases with different charge carrier concentrations. Long-range Coulomb interaction should drive the nano-scale phase-separated state into a self-organized ordered phase, even though such ordering is most likely frustrated by chemical disorder. Identifying this nano-scale self-organization should clarify a number of confusing issues related to the origin of the superconductivity in the cuprates.