Describing How the Superconducting Transition in La2CuO4+y Is Related to the i-O Phase Separation

The phase separation of oxygen interstitial in the spacer layers separating the CuO2 planes in the high critical temperature superconductor La2CuO4+y was studied by Poccia et al. (Nat. Mater. 10:733, 2011). We model this transition by the electronic charge in the planes that can be described by the Cahn-Hilliard theory, with the formation of clusters of low and high densities separated by potential barriers. The charge diffusion into bound regions minimizes the energy and favors the formation of Cooper pairs. Self-consistent calculations yield local dependent superconducting amplitudes Delta (sc)(r), and the resistivity transition at T (c) is driven by Josephson coupling among these nanoscale clusters.