Voltage-controlled Group Velocity of Edge Magnetoplasmon in the Quantum Hall Regime

TL;DR

This study measures how the group velocity of edge magnetoplasmons in the quantum Hall regime can be controlled by gate voltage, revealing the impact of electrostatic screening on EMP propagation speed.

Contribution

It demonstrates voltage-controlled modulation of EMP group velocity via gate-induced screening effects in the quantum Hall regime.

Findings

EMP group velocity depends on gate voltage

Screening by metallic gates reduces EMP velocity

Velocity variation correlates with gate-edge distance

Abstract

We investigate the group velocity of edge magnetoplasmons (EMPs) in the quantum Hall regime by means of time-of-flight measurement. The EMPs are injected from an Ohmic contact by applying a voltage pulse, and detected at a quantum point contact by applying another voltage pulse to its gate. We find that the group velocity of the EMPs traveling along the edge channel defined by a metallic gate electrode strongly depends on the voltage applied to the gate. The observed variation of the velocity can be understood to reflect the degree of screening caused by the metallic gate, which damps the in-plane electric field and hence reduces the velocity. The degree of screening can be controlled by changing the distance between the gate and the edge channel with the gate voltage.