Non linear transport properties of an insulating YBCO nano-bridge

We have investigated the transport properties of an insulating sub-micrometric YBa2Cu3O7-d bridge, patterned on a thin film. As expected for a variable-range-hopping insulator, transport is found non linear. The reduced dimension allows for the observation of an individual fluctuator generating random telegraph noise, which dynamics could be explored as a function of the temperature and transport current. Some recordings clearly exhibit three levels fluctuating resistance, with comparable level separation and correlated dynamics, which likely result from the existence of two states or correlated clustered charge traps.