The Dip Effect under Integer Quantized Hall Conditions

TL;DR

This paper investigates the dip effect in the integer quantum Hall regime, combining theoretical modeling with experimental measurements to understand how edge electrostatics influence transport anomalies in 2D electron gases.

Contribution

It provides a semi-analytical screening theory model explaining the dip effect and validates it with experimental data on GaAs/AlGaAs heterostructures.

Findings

The dip effect amplitude is strongly affected by edge electrostatics.

Narrower incompressible strips lead to a more pronounced dip effect.

The theoretical predictions align well with experimental observations.

Abstract

In this work we investigate an unusual transport phenomenon observed in two-dimensional electron gas under integer quantum Hall effect conditions. Our calculations are based on the screening theory, using a semi-analytical model. The transport anomalies are \emph{dip} and overshoot effects, where the Hall resistance decreases (or increases) unexpectedly at the quantized resistance plateaus intervals. We report on our numerical findings of the \emph{dip} effect in the Hall resistance, considering GaAs/AlGaAs heterostructures in which we investigated the effect under different experimental conditions. We show that, similar to overshoot, the amplitude of the dip effect is strongly influenced by the edge reconstruction due to electrostatics. It is observed that the steep potential variation close to the physical boundaries of the sample results in narrower incompressible strips, hence, the experimental observation of the dip effect is limited by the properties of these current carrying strips. By performing standard Hall resistance measurements on gate defined narrow samples, we demonstrate that the predictions of the screening theory is in well agreement with our experimental findings.