Dependence of the 0.5(2e2/h) conductance plateau on the aspect ratio of InAs quantum point contacts with in-plane side gates

TL;DR

This study investigates how the aspect ratio of InAs quantum point contacts influences the 0.5 conductance plateau, revealing that larger aspect ratios enhance the plateau's stability and are linked to electron-electron interactions, aiding spintronic device development.

Contribution

It demonstrates that increasing the aspect ratio of InAs QPCs extends the 0.5 conductance plateau, highlighting the role of electron interactions and guiding spintronic device design.

Findings

Larger aspect ratios increase the 0.5 conductance plateau range.

Electron-electron interactions become more significant with higher aspect ratios.

Asymmetrically biased QPCs with large aspect ratios can improve spin injector/detector performance.

Abstract

The observation of a 0.5 conductance plateau in asymmetrically biased quantum point contacts with in-plane side gates has been attributed to the onset of spin-polarized current through these structures. For InAs quantum point contacts with the same width but longer channel length, there is roughly a fourfold increase in the range of common sweep voltage applied to the side gates over which the 0.5 conductance plateau is observed when the QPC aspect ratio (ratio of length over width of the narrow portion of the structure) is increased by a factor 3. Non-equilibrium Green s function simulations indicate that the increase in the size of the 0.5 conductance plateau is due to an increased importance, over a larger range of common sweep voltage, of the effects of electron-electron interactions in QPC devices with larger aspect ratio. The use of asymmetrically biased QPCs with in-plane side gates and large aspect ratio could therefore pave the way to build robust spin injectors and detectors for the successful implementation of spin field effect transistors