Novel Differential Conductance Oscillations in Asymmetric Quantum Point Contacts

TL;DR

This paper reports the observation and systematic study of differential conductance oscillations in asymmetric quantum point contacts, revealing their suppression under magnetic fields and temperature, and suggesting electron correlation effects as their origin.

Contribution

It introduces the discovery of conductance oscillations in asymmetric QPCs and analyzes their suppression, proposing electron correlations as the underlying cause.

Findings

Oscillations are suppressed by magnetic field and temperature.

Temperature effects can be simulated by Fermi distribution smearing.

Single particle models do not explain the oscillations.

Abstract

Small differential conductance oscillations as a function of source-drain bias were observed and systematically studied in an asymmetric quantum point contact (QPC). These oscillations become significantly suppressed in a small in-plane magnetic field ($\sim~0.7~T$) or at higher temperatures ($\sim~800~mK$). 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.