Antiphased Cyclotron-Magnetoplasma Mode in a Quantum Hall System

TL;DR

This study investigates a unique quantum magnetoplasma mode in a 2D electron gas using inelastic light scattering, revealing a zero-momentum energy gap caused by electron-electron interactions, with results supported by theoretical calculations.

Contribution

It presents the first experimental observation and theoretical analysis of the antiphased magnetoplasma mode, highlighting its quantum nature and the lifting of zero momentum degeneracy.

Findings

Zero momentum degeneracy is lifted for the modes.

The energy gap is due to a negative correlation shift.

The shift is proportional to the effective Rydberg constant.

Abstract

An antiphased magnetoplasma (MP) mode in a two-dimensional electron gas (2DEG) has been studied by means of inelastic light scattering (ILS) spectroscopy. Unlike the cophased MP mode it is purely quantum excitation which has no classic plasma analogue. It is found that zero momentum degeneracy for the antiphased and cophased modes predicted by the first-order perturbation approach in terms of the {\it e-e} interaction is lifted. The zero momentum energy gap is determined by a negative correlation shift of the antiphased mode. This shift, observed experimentally and calculated theoretically within the second-order perturbation approach, is proportional to the effective Rydberg constant in a semiconductor material.