Optical Hall Effect in the Integer Quantum Hall Regime

TL;DR

This study measures the optical Hall conductivity in a quantum Hall system using Faraday rotation, revealing a plateau-like feature in the terahertz regime that suggests carrier localization effects influence the optical response.

Contribution

First observation of plateau-like structures in optical Hall conductivity in the terahertz regime, linking optical measurements to quantum Hall phenomena.

Findings

Faraday rotation deviates from Drude behavior near ν=2

Plateau-like structure observed in optical Hall conductivity

Results suggest localization effects influence optical response

Abstract

Optical Hall conductivity $\sigma_{xy}(\omega)$ is measured from the Faraday rotation for a GaAs/AlGaAs heterojunction quantum Hall system in the terahertz frequency regime. The Faraday rotation angle ($\sim$ fine structure constant $\sim$ mrad) is found to significantly deviate from the Drude-like behavior to exhibit a plateau-like structure around the Landau-level filling $\nu=2$. The result, which fits with the behavior expected from the carrier localization effect in the ac regime, indicates that the plateau structure, although not quantized, still exists in the terahertz regime.