Electron spin relaxation as evidence of excitons in an electron-hole plasma

TL;DR

This study uses electron spin relaxation measurements in a GaAs quantum well to detect excitonic features across a wide range of densities and temperatures, revealing persistent excitonic signatures.

Contribution

It demonstrates a novel method to identify excitonic effects in electron-hole systems through spin relaxation, even at high densities and temperatures.

Findings

Excitonic signatures are observed at high densities and temperatures.

Spin relaxation reveals Coulomb interaction effects.

Transition from localized excitons to electron-hole plasma is characterized.

Abstract

We exploit the influence of the Coulomb interaction between electrons and holes on the electron spin relaxation in a (110)-GaAs quantum well to unveil excitonic signatures within the many particle electron-hole system. The temperature dependent time- and polarization-resolved photoluminescence measurements span five decades of carrier density, comprise the transition from localized excitons over quasi free excitons to an electron-hole plasma, and reveal strong excitonic signatures even at relatively high densities and temperatures.