Abstract
The photoluminescence of annealed CdxZn1−xSe quantum dots (QDs) under the influence of an external magnetic field has been studied in this paper. Post-growth annealing was performed for different annealing times. Above a critical annealing time, the QD luminescence shows a pronounced red-shift of the Zeeman split magnetic subcomponents. This observation is in contrast to the blue-shift caused by the diamagnetic behavior that is usually observed in non-magnetic QDs. We attribute our finding to the paramagnetism caused by the mixing of heavy and light hole states. Hence, post-growth thermal annealing treatment might be employed to render undoped epitaxial QDs intrinsically magnetic in a controlled manner. Two theoretical models were developed: a few-particle model to account for excitonic complex effects and a multiband calculation that describes the valence band hybridization. Contrasting the two models allowed us to unambiguously elucidate the nature of such an effect.
Highlights
The photoluminescence of annealed Cdx Zn1−x Se quantum dots (QDs) under the influence of an external magnetic field has been studied in this paper
Their counterparts, the light holes, are commonly believed to play only a minor role in the exciton ground state due to the lifting of lh–hh degeneracy provoked by strain fields and quantum confinement
By modifying the dimensions and composition of the QDs, the lh can contribute to the exciton ground state [6] and, as proved here, effectively tune the exciton magnetic behavior
Summary
The photoluminescence of annealed Cdx Zn1−x Se quantum dots (QDs) under the influence of an external magnetic field has been studied in this paper. We show how to control the intrinsic QD magnetism by means of thermal annealing (TA), taking into account the presence of extra charges and exchange effects as well as the total angular momentum tuning of the ground state.
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