Probing the spin states of three interacting electrons in quantum dots

TL;DR

This study uses resonant inelastic light scattering to observe a low-energy spin mode in three interacting electrons within quantum dots, providing insights into ferromagnetism at the quantum level.

Contribution

It demonstrates a novel method to probe spin states in quantum dots and links observed modes to Stoner ferromagnetism in a minimal electron system.

Findings

Identification of a sharp spin mode in three-electron quantum dots

Suppression of inhomogeneous broadening enables clearer spectra

Support for the mode as a probe of Stoner ferromagnetism

Abstract

We observe a low-lying sharp spin mode of three interacting electrons in an array of nanofabricated AlGaAs/GaAs quantum dots by means of resonant inelastic light scattering. The finding is enabled by a suppression of the inhomogeneous contribution to the excitation spectra obtained by reducing the number of optically-probed quantum dots. Supported by configuration-interaction calculations we argue that the observed spin mode offers a direct probe of Stoner ferromagnetism in the simplest case of three interacting spin one-half fermions.