Observation of excess resistance anomaly at resistive transitions in Ag/Au nanostructures
The resistive transition in nanocomposite films of silver (Ag) nanoclusters of ~ 1 nm diameter embedded in gold (Au) matrix exhibits an anomalous resistance peak at the onset of the transition, even for transition temperatures as high as 260 K. The maximum value of the resistance ranges between ~ 30% - 300% above that of the normal state depending on devices as well as lead configuration within a single device. The excess resistance regime was observed in about 10% of the devices, and extends from ~ 10 - 100 K. Application of magnetic field of 9 T was found to partially suppress the excess resistance. From the critical current behavior, as well as negative differential resistance in the current-voltage characteristics, we discuss the possibility of interacting phase slip centers and alternate physical scenarios that may cause the excess resistance in our system.