Magnetic polarons in a single diluted magnetic semiconductor quantum dot

Quasi-zero-dimensional magnetic polarons in single ${\mathrm{Cd}}_{0.93}{\mathrm{Mn}}_{0.07}{\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{0.6}{\mathrm{Mg}}_{0.4}\mathrm{Te}$ quantum dots have been studied by photoluminescence spectroscopy. By comparing the experimental data with model calculations, the energy, the internal magnetic field, and the volume of the magnetic polarons are obtained. Moreover, the magnetic environment of the recombining electron hole pair causes a distinct broadening of the emission line $(\ensuremath{\sim}4 \mathrm{meV})$ of one diluted magnetic single quantum dot. The alignment of the Mn-spins in high magnetic fields results in a linewidth narrowing of almost one order of magnitude and the linewidth becomes comparable to that of a nonmagnetic ${\mathrm{Cd}}_{0.93}{\mathrm{Mg}}_{0.07}{\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{0.6}{\mathrm{Mg}}_{0.4}\mathrm{Te}$ reference sample.