Anomalous enhancement of the superconducting transition temperature of electron-doped La2-xCexCuO4 and Pr2-xCexCuO4 cuprate heterostructures

The superconducting transition temperature T-c of multilayers of electron-doped cuprates, composed of underdoped (or undoped) and overdoped La2-xCexCuO4 (LCCO) and Pr2-xCexCuO4 (PCCO) thin films, is found to increase significantly with respect to the T-c of the corresponding single-phase films. By investigating the critical current density of superlattices with different doping levels and layer thicknesses, we find that the T-c enhancement is caused by a redistribution of charge over an anomalously large distance.