Direct measurements of the local electron transport properties in YBaCuO superconducting thin films

Abstract

We have made measurements of the local potential distribution and topography of current carrying Y1Ba2Cu3O6.9 thin films using a scanning tunneling microscope. We have compared the electrostatic potential distribution in the normal state on post-annealed thin films and in-situ prepared films. On post-annealed films we find steps in the potential image indicative of insulating boundaries in the material which occur at boundaries between clusters of grains whereas the in-situ films show a nearly uniform potential drop. These results provide a clear indication of the nature of disorder in these thin films and what length scale ultimately determines the microscopic resistivity.