Reentrant Formation of Magnetic Polarons in Quantum Dots

TL;DR

This paper models magnetic polaron formation in doped quantum dots, revealing a reentrant magnetization effect with potential experimental signatures, and confirms its robustness beyond mean field approximations.

Contribution

It introduces a new model showing reentrant magnetic polaron behavior in quantum dots, supported by statistical analysis and spectral predictions.

Findings

Reentrant magnetization occurs at specific temperatures.

The effect persists beyond mean field approximation.

Photoluminescence spectra show signatures of reentrant polarons.

Abstract

We propose a model of magnetic polaron formation in semiconductor quantum dots doped with magnetic ions. A wetting layer serves as a reservoir of photo-generated holes, which can be trapped by the adjacent quantum dots. For certain hole densities, the temperature dependence of the magnetization induced by the trapped holes is reentrant: it disappears for some temperature range and reappears at higher temperatures. We demonstrate that this peculiar effect is not an artifact of the mean field approximation and persists after statistical spin fluctuations are accounted for. We predict fingerprints of reentrant magnetic polarons in photoluminescence spectra.