Electronic phase separation near the superconductor-insulator transition ofNd1+xBa2−xCu3O7−δthin films studied by an electric-field-induced doping effect

Abstract

We report a detailed study of the transport properties of ${\text{Nd}}_{1+x}{\text{Ba}}_{2\ensuremath{-}x}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ thin films with doping changed by field effect. The data cover the whole superconducting to insulating transition and show remarkable similarities with the effect of chemical doping in high critical temperature superconductors. The results suggest that the add-on of carriers is accompanied by an electronic phase separation, independent on the details of the doping mechanism.