Nano-scale complexities in the superconducting cuprates

Underdoped cuprates are characterized by nano-scale complexity with strong spatial variation in the electronic properties, including superconductivity. It is often assumed that the stripe order underlies this spatial complexity, but the evidence of local stripe order in the superconducting phase is weak. We propose an alternative idea of electronically driven two-dimensional local order that leads to phase separation in the reciprocal space, which could be the basis for two-component superconductivity. (C) 2008 Elsevier Ltd. All rights reserved.