Influence of exciton spin relaxation on the photoluminescence spectra of semimagnetic quantum dots

TL;DR

This study combines experimental and theoretical approaches to analyze how exciton spin relaxation influences the photoluminescence spectra of single CdMnTe quantum dots with varying Mn content, revealing detailed spin dynamics and material parameters.

Contribution

It provides a detailed analysis of exciton spin relaxation effects on photoluminescence spectra and introduces a method to evaluate quantum dot parameters from spectral data.

Findings

Identification of three stages of exciton-Mn spin system equilibration.

Asymmetric photoluminescence spectra due to intermediate spin relaxation stage.

Quantitative evaluation of localization volume, Mn ions, and temperature for individual dots.

Abstract

We present a comprehensive experimental and theoretical studies of photoluminescence of single CdMnTe quantum dots with Mn content x ranging from 0.01 to 0.2. We distinguish three stages of the equilibration of the exciton-Mn ion spin system and show that the intermediate stage, in which the exciton spin is relaxed, while the total equilibrium is not attained, gives rise to a specific asymmetric shape of the photoluminescence spectrum. From an excellent agreement between the measured and calculated spectra we are able to evaluate the exciton localization volume, number of paramagnetic Mn ions, and their temperature for each particular dot. We discuss the values of these parameters and compare them with results of other experiments. Furthermore, we analyze the dependence of average Zeeman shifts and transition linewidths on the Mn content and point out specific processes, which control these values at particular Mn concentrations.