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

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 noninverted InAs/InxGa1-xSb 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.

Automated summary

This paper presents a versatile on-chip time-resolved transport measurement scheme applicable to narrow-gap systems. The authors conducted experiments on noninverted InAs/InxGa1-xSb composite quantum wells and observed pulsed charge waveforms for both electrons and holes. They found that the group velocity of edge magnetoplasmon pulses is reduced and broadened in both the electron and hole regimes, suggesting the influence of charge puddles in the bulk.