Tuning the properties of magnetic CdMnTe quantum dots

TL;DR

This paper demonstrates a method to create magnetic CdMnTe quantum dots with tunable spin properties by controlling Mn ion deposition and thermal annealing, affecting their optical and magnetic characteristics.

Contribution

It introduces a novel fabrication process for magnetic quantum dots with adjustable properties through Mn ion deposition and annealing.

Findings

Single-dot emission lines confirmed Mn incorporation.

Magnetic fluctuations cause 3 meV linewidth, reduced to 0.25 meV after annealing.

Thermal annealing increases quantum dot size, reducing magnetic fluctuation effects.

Abstract

We show that CdMnTe self-assembled quantum dots can be formed by depositing a submonolayer of Mn ions over a ZnTe surface prior to deposition of the CdTe dot layer. Single dot emission lines and strongly polarized quantum dot photoluminescence in an applied magnetic field confirm the presence of Mn in individual quantum dots. The width of PL lines of the single CdMnTe dots is 3 meV due to magnetic moment fluctuations of the Mn ions. After rapid thermal annealing, the emission lines of individual magnetic quantum dots narrow significantly to 0.25 meV showing that effect of magnetic fluctuations is strongly reduced most probably due to an increase in the average quantum dot size. These results suggest a way to tune the spin properties of magnetic quantum dots.