Effect of charge state in nearby quantum dots on quantum Hall effect

TL;DR

This study investigates how the charge state of quantum dots affects the quantum Hall effect in a nearby two-dimensional electron system, revealing charge-dependent suppression of magnetoresistance linked to spin interactions.

Contribution

It demonstrates the influence of quantum dot charge states on quantum Hall transport properties, highlighting spin-flip processes as a key mechanism.

Findings

Quantum Hall features persist despite proximity of QDs

Positive gate voltage suppresses magnetoresistance at $ u<1$

Charge state in QDs affects 2DES transport via spin excitation

Abstract

Magnetoresistance measurements have been performed on a gated two-dimensional electron system (2DES) separated by a thin barrier layer from a layer of InAs self-assembled quantum dots (QDs). Clear features of the quantum Hall effect were observed despite the proximity of the QDs layer to the 2DES. However, the magnetoresistance ($\rho_{xx}$) and Hall resistance ($\rho_{xy}$) are suppressed significantly in the magnetic field range of filling factor $\nu<1$ when a positive voltage is applied to the front gate. The influence of the charge state in QDs was observed on the transport properties of the nearby 2DES only in the field range of $\nu < 1$. It is proposed that the anomalous suppression of $\rho_{xx}$ and $\rho_{xy}$ is related to spin excitation, which is induced by spin-flip processes involving electrons in the QDs and the 2DES.