Tunable rectification and slope reversals in the I-V characteristics of ballistic nanojunctions

We investigate nonlinear effects at low temperature in the I-V characteristics of four-terminal nanojunctions fabricated from InGaAs/ InAlAs heterostructures. The rectified voltage can be tuned by applying biases on side gates, as well as by changing cooldown conditions, i.e., by controlling the conductances of the junctions' channels. In addition, we observe reversals in the slope of the I-V curves as the probe current grows. These reversals coincide with abrupt changes in the channels' conductances. We discuss possible interpretations of these observations, and provide a comparison with previous experimental results.