Local investigation of the energy gap within the incompressible strip in the quantum Hall regime

TL;DR

This study investigates the local energy gap at the quantum Hall edge, revealing a significant enhancement over single-particle predictions and highlighting the influence of mobility and magnetic fields on the gap.

Contribution

It provides the first local measurements of the energy gap in the incompressible strip at the quantum Hall edge across different sample mobilities, emphasizing the role of mobility and magnetic field effects.

Findings

Energy gap is strongly enhanced compared to Zeeman splitting.

Measured gap is identified as a mobility gap.

In-plane magnetic field affects the gap through spin and broadening effects.

Abstract

We experimentally study the energy gap within the incompressible strip at local filling factor $\nu_c=1$ at the quantum Hall edge for samples of very different mobilities. The obtained results indicate strong enhancement of the energy gap in comparison to the single-particle Zeeman splitting. We identify the measured gap as a mobility gap, so a pronounced experimental in-plane magnetic field dependence can both be attributed to the spin effects as well as to the change in the energy levels broadening.