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

TL;DR

This study investigates how the 0.7 conductance anomaly in quantum wires depends on the potential barrier's curvature, revealing that lower curvature enhances the anomaly's prominence and shifts its occurrence.

Contribution

It demonstrates that the curvature of the potential barrier primarily influences the 0.7 anomaly, using statistical analysis of measurements from an array of quantum wires.

Findings

0.7 anomaly becomes more pronounced at lower barrier curvature

The anomaly occurs at lower conductance values with decreased curvature

Other conductance properties are less influential on the 0.7 structure

Abstract

Ninety eight one-dimensional channels defined using split gates fabricated on a GaAs/AlGaAs heterostructure are measured during one cooldown at 1.4 K. The devices are arranged in an array on a single chip, and individually addressed using a multiplexing technique. The anomalous conductance feature known as the "0.7 structure" is studied using statistical techniques. The ensemble of data show that the 0.7 anomaly becomes more pronounced and occurs at lower values as the curvature of the potential barrier in the transport direction decreases. This corresponds to an increase in the effective length of the device. The 0.7 anomaly is not strongly influenced by other properties of the conductance related to density. The curvature of the potential barrier appears to be the primary factor governing the shape of the 0.7 structure at a given T and B.