Conductance Anomaly and Fano Factor Reduction in Quantum Point Contacts

Abstract

We report an experimental study on the shot noise as well as the dc transport properties of a quantum point contact (QPC) whose conductance anomaly can be tuned electrostatically by the gate electrodes. By controlling the single QPC so that it has no anomaly or an anomaly at $0.5G_0$, $0.8G_0$ or $0.9G_0$ ($G_0=2e^2/h$), we prove that the anomaly always accompanies the Fano factor reduction due to the asymmetric transmission of the two spin-dependent channels for the conductance lower than $G_0$. For the QPC tuned to have the anomaly at $0.5G_0$ the channel asymmetry is found to be as large as 67% with the spin gap energy gradually evolving as the conductance increases.

RevTex, 4 pages, 3 figures

References in corpus (2)

• Effects of short-range interactions on transport through quantum point contacts: A numerical approach
• Tunable 0.7 conductance plateau in quantum dots