Scanning Gate Spectroscopy of transport across a Quantum Hall Nano-Island

TL;DR

This study uses scanning gate spectroscopy to investigate electron transport and Coulomb blockade effects in a quantum Hall nano-island, revealing its discrete energy spectrum and confinement characteristics.

Contribution

It demonstrates the application of scanning gate spectroscopy to analyze a quantum Hall nano-island's energy spectrum and transport properties, providing new insights into electronic confinement.

Findings

Coulomb diamonds confirm Coulomb blockade governs transport.

Discrete energy spectrum observed due to electronic confinement.

Estimated potential gradient and edge state velocity.

Abstract

We explore transport across an ultra-small Quantum Hall Island (QHI) formed by closed quan- tum Hall edge states and connected to propagating edge channels through tunnel barriers. Scanning gate microscopy and scanning gate spectroscopy are used to first localize and then study a single QHI near a quantum point contact. The presence of Coulomb diamonds in the spectroscopy con- firms that Coulomb blockade governs transport across the QHI. Varying the microscope tip bias as well as current bias across the device, we uncover the QHI discrete energy spectrum arising from electronic confinement and we extract estimates of the gradient of the confining potential and of the edge state velocity.