Gate tuning of fractional quantum Hall states in InAs two-dimensional electron gas

TL;DR

This study demonstrates gate-tunable fractional quantum Hall states in an InAs 2DEG, revealing how electric field control can induce and modify these states, with implications for quantum electronic devices.

Contribution

It is the first to show gate tuning of FQH states in InAs 2DEG, highlighting the role of quantum well symmetry and disorder sources in their emergence.

Findings

FQH states observed at multiple filling factors at 24 T

Gate voltage controls the emergence of certain FQH states

Interface roughness significantly affects electron mobility and FQH visibility

Abstract

We report the observation of fractional quantum Hall (FQH) effects in a two-dimensional electron gas (2DEG) confined to an InAs/AlGaSb quantum well, using a dual-gated Hall-bar device allowing for the independent control of the vertical electric field and electron density. At a magnetic field of 24 T, we observe FQH states at several filling factors, namely $\nu = 5/3$, $2/3$, and $1/3$, in addition to the $\nu = 4/3$ previously reported for an InAs 2DEG. The $\nu = 4/3$ and $5/3$ states, which are absent at zero back-gate voltage, emerge as the quantum well is made more symmetric by applying a positive back-gate voltage. The dependence of zero-field electron mobility on the quantum-well asymmetry reveals a significant contribution of interface-roughness scattering, with much stronger scattering at the lower InAs/AlGaSb interface. However, the dependence of the visibility of the FQH effects on the quantum-well asymmetry is not entirely consistent with that of mobility, suggesting that a different source of disorder is also at work.