Differential Conductance Oscillations In Asymmetric Quantum Point Contacts

Small differential conductance oscillations as a function of source-drain bias are observed and systematically studied in an asymmetric quantum point contact. These oscillations become significantly suppressed in a small in-plane magnetic field (similar to 0.7 T) or at higher temperatures (similar to 800 mK). Qualitatively, their temperature evolution can be simulated numerically based on smearing of the Fermi distribution, whereas features near zero bias cannot. Single-particle scenarios are unsatisfactory in accounting for the oscillations, suggesting that they are likely caused by electron-and spin-correlation effects.