Sign reversal and tunable rectification in a ballistic nanojunction

Low-temperature measurements show that an asymmetric mesoscopic junction patterned in a two-dimensional electron gas can exhibit tunable rectification, including sign reversal. Strikingly, we observe that the amplitude and sign of the effect are governed by the conductances of the channels and that rectification is reversed without reversing the asymmetry of the device. Based on the temperature dependence of the rectified voltage, we show that the effect is ballistic and exhibits unexpected features with respect to predictions of available models.