Abstract
We report a conductance asymmetry of quantum point contacts (QPC) at near-zero applied current biases. The asymmetry is measured at low temperatures as a rectified dc voltage response to an applied small amplitude ac current. When measured as a function of negative gate-voltage, the rectified signal oscillates. For some of the samples this oscillatory behavior scales linearly with the applied ac current amplitude, which indicates only one step-like non-linearity in differential resistance vs. current. The value of the step is of the order of a few tens of Ohms on a background of several kOhms, and embedded in intrinsic random telegraph signal (RTS) noise. The step could be verified also by a direct measurement of differential resistance vs. dc current. We believe a two-level impurity configuration near the constriction is responsible for the step-like differential resistance.
Original language | English |
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Journal | Physica B: Condensed Matter |
Volume | 194 |
Pages (from-to) | 1131-1132 |
ISSN | 0921-4526 |
Publication status | Published - 1994 |
Externally published | Yes |
Event | 20th International Conference on Low Temperature Physics - Eugne, OR, United States Duration: 4 Aug 1993 → 11 Aug 1993 Conference number: 20 |
Conference
Conference | 20th International Conference on Low Temperature Physics |
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Number | 20 |
Country/Territory | United States |
City | Eugne, OR |
Period | 04/08/1993 → 11/08/1993 |