Studies of resistance switching effects in metal/YBa2Cu3O7a degree x interface junctions

Current-voltage characteristics of planar junctions formed by an epitaxial c-axis oriented YBa2Cu3O7a degree x thin film micro-bridge and Ag counter-electrode were measured in the temperature range from 4.2K to 300K. A hysteretic behavior related to switching of the junction resistance from a high-resistive to a low-resistive state and vice-versa was observed and analyzed in terms of the maximal current bias and temperature dependence. The same effects were observed on a sub-micrometer scale YBa2Cu3O7a degree x thin film-PtIr point contact junctions using Scanning Tunneling Microscope. These phenomena are discussed within a diffusion model, describing an oxygen vacancy drift in YBa2Cu3O7a degree x films in the nano-scale vicinity of the junction interface under applied electrical fields.