The structure of a single sharp quantum Hall edge probed by momentum-resolved tunneling

TL;DR

This study uses momentum-resolved tunneling spectroscopy to investigate the detailed structure of a single sharp quantum Hall edge, revealing inter-channel distances smaller than fundamental length scales and features due to ground energy fluctuations.

Contribution

It demonstrates that epitaxially overgrown cleaved edges provide a sharp edge limit, challenging the applicability of the traditional Chklovskii model for soft edges.

Findings

Inter-channel distances smaller than magnetic length and Bohr radius.

Edge filling factor matches bulk value.

Features attributed to ground energy fluctuations.

Abstract

Momentum resolved magneto-tunnelling spectroscopy is performed at a single sharp quantum Hall edge. We directly probe the structure of individual integer quantum Hall (QH) edge modes, and find that an epitaxially overgrown cleaved edge realizes the sharp edge limit, where the Chklovskii picture relevant for soft etched or gated edges is no longer valid. The Fermi wavevector in the probe quantum well probes the real-space position of the QH edge modes, and reveals inter-channel distances smaller than both the magnetic length and the Bohr radius. We quantitatively describe the lineshape of principal conductance peaks and deduce an edge filling factor from their position consistent with the bulk value. We observe features in the dispersion which are attributed to fluctuations in the ground energy of the quantum Hall system.