Realistic modelling of quantum point contacts subject to high magnetic fields and with current bias at out of linear response regime

TL;DR

This paper models quantum point contacts under high magnetic fields and current bias, revealing how incompressible strips form and influence current distribution, especially out of linear response, with surface charges affecting confinement.

Contribution

It provides a realistic 3D self-consistent model of QPCs under high magnetic fields and bias, highlighting asymmetries in current distribution in the non-linear regime.

Findings

Incompressible strips form under magnetic fields and influence current flow.

Surface charges significantly affect confinement potential.

Large bias induces spatial asymmetry in current-carrying regions.

Abstract

The electron and current density distributions in the close proximity of quantum point contacts (QPCs) are investigated. A three dimensional Poisson equation is solved self-consistently to obtain the electron density and potential profile in the absence of an external magnetic field for gate and etching defined devices. We observe the surface charges and their apparent effect on the confinement potential, when considering the (deeply) etched QPCs. In the presence of an external magnetic field, we investigate the formation of the incompressible strips and their influence on the current distribution both in the linear response and out of linear response regime. A spatial asymmetry of the current carrying incompressible strips, induced by the large source drain voltages, is reported for such devices in the non-linear regime.