Extreme sensitivity of the spin-splitting and 0.7 anomaly to confining potential in one-dimensional nanoelectronic devices

TL;DR

This study investigates how the electron g-factor and 0.7 anomaly in quantum point contacts are highly sensitive to the confining potential, revealing potential pathways to optimize spintronic device performance.

Contribution

It demonstrates the extreme sensitivity of the g-factor and 0.7 anomaly to confinement potential, highlighting the importance of potential management in QPCs for spintronics.

Findings

g* values up to 2.8 for lowest 1D subband

g* highly sensitive to confinement potential

0.7 anomaly also sensitive to confining potential

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 x 2e^2/h anomaly. We report on the dependence of the 1D Lande 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.