Inter‐dot spin exchange interaction in coupled II–VI semiconductor quantum dots

Abstract

Abstract We have performed polarization selective photoluminescence (PL) experiment on a series of self‐assembled quantum dots (QDs) in the form of single‐ and double‐QD layer systems. The double layers were formed from diluted magnetic semiconductor (DMS) (either CdMnSe or CdZnMnSe) and non‐DMS (either CdSe or CdZnSe) layers, separated by non‐DMS ZnSe barriers. The peaks from DMS and non‐DMS QD layers are clearly resolved in the PL spectra taken at zero magnetic field. When a magnetic field is applied to the double layer QD (DLQD) system, the intensities of the circularly polarized PL peaks corresponding to the non‐DMS (i.e., CdSe and CdZnSe) layers exhibit significant changes, reflecting correspondingly large changes in the degrees of spin polarization of the non‐DMS QDs. This enhancement of spin polarization observed in the double‐layer QD structures is interpreted in terms of anti‐parallel spin interaction between carriers localized in the coupled QD pairs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)