The anomalous negative acoustoelectric current in single-electron transport devices

We investigate the anomalous negative oscillations present in the frequency dependence of an acoustoelectric current by using surface acoustic wave devices. The time domain responses of the transmission performances for our devices show that the Bragg reflections from the second transducer have a strong effect. On the basis of the results measured, a new model is advanced for explaining the anomalous negative oscillations present in the I(f)I(f) characteristics. In addition, in the negative direction, the acoustoelectric current measured as a function of the gate voltage is observed to be quantized. And the interpretation for the negative quantized plateaus present in the II(Vg) characteristics is also given.