Extreme Sensitivity of the Spin-Splitting and 0.7 Anomaly to Confining Potential in One-Dimensional Nanoelectronic Devices

Abstract

Quantum point contacts (QPCs) have shown promise as nanoscale spin-selective components for spintronic applications and are of fundamental interest in the study of electron many-body effects such as the 0.7 × 2e(2)/h anomaly. We report on the dependence of the 1D Landé g-factor g and 0.7 anomaly on electron density and confinement in QPCs with two different top-gate architectures. We obtain g values up to 2.8 for the lowest 1D subband, significantly exceeding previous in-plane g-factor values in AlGaAs/GaAs QPCs and approaching that in InGaAs/InP QPCs. We show that g is highly sensitive to confinement potential, particularly for the lowest 1D subband. This suggests careful management of the QPC's confinement potential may enable the high g desirable for spintronic applications without resorting to narrow-gap materials such as InAs or InSb. The 0.7 anomaly and zero-bias peak are also highly sensitive to confining potential, explaining the conflicting density dependencies of the 0.7 anomaly in the literature.

Dependence of the 0.7 anomaly on the curvature of the potential barrier in quantum wires

“…Data from nine studies are summarized in Ref. [21], showing that the 0.7 structure is highly sensitive to the 1D confining potential. It is likely that the specific potential landscape varies between these devices, due to differences in structure, material, and geometry.…”

Odd and even Kondo effects from emergent localization in quantum point contacts

“…The ubiquity of the phenomenon, and the fact that such double-peak ZBAs were persistently observed in the same devices over different cool-downs, implies that it is a generic effect and not due to a fortuitous impurity nearby. Figure 1 presents data from two QPC 2F to illustrate that the signatures of many-body physics show qualitatively similar features, though with significant device-to-device variation (whereas there is no strong variation in the manifestation of non-interacting electron physics, such as the quantized conductance 8,10 ). Figure 1b, c presents measurements of the linear conductance (Methods).…”

Enhancement Mechanism of the ElectrongFactor in Quantum Point Contacts

“…Refs. [6][7][8][9][10]. In spite of 20 years of studies there is no consensus about the mechanism of the 0.7 & ZBA.…”