Suris tetrons: possible spectroscopic evidence for four-particle optical excitations of the 2D electron gas

TL;DR

This paper presents spectroscopic evidence for four-particle excitations, called Suris tetrons, in a 2D electron gas, bridging the understanding of optical excitations at intermediate carrier densities.

Contribution

It introduces a new interpretation of optical transitions in 2D electron gases involving Suris tetrons, supported by magneto-photoluminescence data.

Findings

Identification of photoluminescence features as Suris tetrons

Analysis of magnetic-field behavior supports four-particle excitation model

Provides a theoretical and experimental link for intermediate density regimes

Abstract

The excitations of a two-dimensional electron gas in quantum wells with intermediate carrier density (~10^{11} cm^{-2}), i.e., between the exciton-trion- and the Fermi-Sea range, are so far poorly understood. We report on an approach to bridge this gap by a magneto-photoluminescence study of modulation-doped (Cd,Mn)Te quantum well structures. Employing their enhanced spin splitting, we analyzed the characteristic magnetic-field behavior of the individual photoluminescence features. Based on these results and earlier findings by other authors, we present a new approach for understanding the optical transitions at intermediate densities in terms of four-particle excitations, the Suris tetrons, which were up to now only predicted theoretically. All characteristic photoluminescence features are attributed to emission from these quasi-particles when attaining different final states.