Abstract
We investigated the dynamics of the interaction between spin-polarized photo-created carriers and Mn ions on InGaAs/GaAs: Mn structures. The carriers are confined in an InGaAs quantum well and the Mn ions come from a Mn delta-layer grown at the GaAs barrier close to the well. Even though the carriers and the Mn ions are spatially separated, the interaction between them is demonstrated by time-resolved spin-polarized photoluminescence measurements. Using a pre-pulse laser excitation with an opposite circular-polarization clearly reduces the polarization degree of the quantum-well emission for samples where a strong magnetic interaction is observed. The results demonstrate that the Mn ions act as a spin-memory that can be optically controlled by the polarization of the photocreated carriers. On the other hand, the spin-polarized Mn ions also affect the spin-polarization of the subsequently created carriers as observed by their spin relaxation time. These effects fade away with increasing time delays between the pulses as well as with increasing temperatures.
Highlights
We observed a clear effect of spin memory for samples where the QW confined carriers present a significant interaction with the Mn ions from a nearby δ Mn layer
We demonstrated that by applying a pre-pulse from an additional excitation beam with an opposite circular polarization gives rise to a reduced polarization degree of the PL emission as compared to the results without the pre-pulse
We propose that the pre-pulse writes the spin information on Mn ions that act as a spin reservoir, and this memory is read by the second pulse as a reduced polarization degree
Summary
We investigated two set of samples that differ by the inclusion of a C delta-doping layer (δ C) at the other QW barrier, which provides additional holes to the InGaAs QW. Without C, the Mn doping position was varied, while in the second set, with C, the Mn concentration was varied.
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