Optical properties of paramagnetic ion-doped semiconductor nanocrystals

We present a theoretical study of the optical properties of quantum dots containing a single paramagnetic ion. The eigenvalue problem of an electron-hole pair in interaction with a localized spin is solved. In Mn-doped nanocrystals of II-VI semiconductors such as CdTe the fundamental absorption line splits into six components, whose relative intensities strongly depend on the Mn spin orientation with respect to the polarization of light, suggesting the possibility of optical detection of spin. With the Mn atom at the center of the quantum dot the overall zero-field splitting is typically an order of magnitude larger than the saturation Zeeman splitting in the bulk diluted magnetic semiconductor with the same average concentration of Mn. The effects of an applied magnetic field are also investigated and recently reported magnetic circular dichroism data in high-quality ZnSe:Mn nanocrystals is discussed.