Effects of Metallic Gates on ac Measurements of the Quantum Hall Resistance

TL;DR

This study investigates how metallic gates influence ac measurements of the quantum Hall resistance, revealing that measurement apparatus effects significantly impact frequency dependence rather than intrinsic properties.

Contribution

The paper demonstrates that dielectric losses and back-gate configurations affect ac quantum Hall resistance measurements, highlighting the importance of measurement setup in observed frequency dependence.

Findings

Frequency coefficient can be controlled by back-gate voltage.

Removing back-gates reduces dielectric losses significantly.

Flat quantum Hall resistance plateau observed at 1 kHz.

Abstract

Using a sample with a split back-gate, a linear frequency dependence of the ac quantum Hall resistance was observed. The frequency coefficient, which is due to dielectric losses produced by leakage current between the 2DEG and the back-gates, can be turned from a positive to a negative values by increasing the back-gate voltage. More interestingly, by removing theses back-gates, the losses can be considerably reduced leading to a residual frequency coefficient on the order of (0.03+-0.03) ppm/kHz. Moreover, at 1 kHz, an extremely flat plateau was observed over a magnetic field range of 1.4 T. These results clearly indicate that the audio frequency dependence of the QHR is to a large extend related to the measurement apparatus and does not originate from the physical transport properties of the 2DEG.