# Fine structure of an exciton coupled to a single Fe2+ ion in a CdSe/ZnSe quantum dot

## TL;DR

This study investigates the exchange interaction between a single Fe2+ ion and a neutral exciton in a CdSe/ZnSe quantum dot, revealing complete degeneracy lifting and detailed polarization characteristics.

## Contribution

It demonstrates the conditions for full degeneracy lifting in exciton-Fe2+ systems, highlighting the roles of anisotropy and zero-field splitting in the spectrum.

## Key findings

- Observation of eight fully linearly-polarized emission lines
- Complete degeneracy lifting in the excitonic spectrum
- Conditions for degeneracy restoration when anisotropy or zero-field splitting are neglected

## Abstract

We present a polarization-resolved photoluminescence study of the exchange interaction effects in a prototype system consisting of an individual Fe2+ ion and a single neutral exciton confined in a CdSe/ZnSe quantum dot. Maximal possible number of eight fully linearly-polarized lines in the bright exciton emission spectrum is observed, evidencing complete degeneracy lifting in the investigated system. We discuss conditions required for such a scenario to take place: anisotropy of the electron-hole interaction and the zero-field splitting of the Fe2+ ion spin states. Neglecting of either of these components is shown to restore partial degeneracy of the transitions, making the excitonic spectrum similar to those previously reported for all other systems of quantum dots with single magnetic dopants.