Time-resolved measurement of ambipolar edge magnetoplasmon transport in InAs/InGaSb composite quantum wells

TL;DR

This paper introduces a versatile on-chip time-resolved transport measurement method for one-dimensional edge states in narrow-gap systems, demonstrating its application to InAs/InGaSb quantum wells and revealing carrier chirality and pulse broadening effects.

Contribution

The study presents a new measurement scheme that does not require quantum point contacts and applies it to ambipolar quantum wells, enabling separate electron and hole regime analysis.

Findings

Demonstrated carrier chirality in quantum Hall regimes

Observed pulse broadening indicating charge puddles

Applied to both electron and hole regimes in a single device

Abstract

Time-resolved charge transport measurement for one-dimensional edge states is a powerful means for investigating nonequilibrium charge dynamics and underlying interaction effects therein. Here, we report a versatile on-chip time-resolved transport measurement scheme that does not require a quantum point contact and is therefore applicable to narrow-gap systems. We apply the technique to non-inverted InAs/In$_{x}$Ga$_{1-x}$Sb composite quantum wells, where its ambipolar character enables us to demonstrate the scheme in both the electron and hole regimes separately using a single device. Time-resolved measurements in the quantum Hall regimes clearly exhibit the chirality of each carrier, with pulsed charge waveforms observed only for one magnetic field direction opposite for electrons and holes. Waveform analysis in the time domain reveals reduced group velocity and broadening of edge magnetoplasmon pulses in both the electron and hole regimes, suggesting the influence of charge puddles in the bulk. Our time-resolved measurement scheme, applicable to various systems, will pave the way for investigations of dynamical properties of exotic topological edge states.