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arXiv · 2310.06651

Inverse exciton spin orientation due to trion formation in modulation doped quantum wells

Lyubov Kotova·Alexei Platonov·Vladimir Kochereshko
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Abstract

Time-resolved and time-integrated circularly polarized photoluminescence of excitons and trions in external magnetic fields up to 10 T has been studied in undoped and n-type doped quantum well structures based on ZnSe. In an undoped structure, a circular polarization of photoluminescence induced by magnetic fields corresponded to the Boltzmann distribution of excitons on Zeeman sublevels. The inverse spin orientation of excitons is observed in doped samples with a carrier density of $3 \times 10^{10}$ cm$^{-2}$ and higher. Model calculations show that the reason for the inverse spin orientation is the effective depletion of the lowest-exciton Zeeman sublevel as a result of the spin-dependent formation of trions. The trion formation time as a result of exciton-electron binding was determined as 2 ps. This is noticeably shorter than the characteristic time of the exciton-photon interaction. The observed effect can be considered as a way of spin manipulation by electric fields.

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Lyubov Kotova, Alexei Platonov, Vladimir Kochereshko. 2023-10-10. Inverse exciton spin orientation due to trion formation in modulation doped quantum wells. https://doi.org/10.1016/j.ssc.2024.115496

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