Quantum kinetic equations for the ultrafast spin dynamics of excitons in diluted magnetic semiconductor quantum wells after optical excitation

Abstract

Quantum kinetic equations of motion for the description of the exciton spin dynamics in II-VI diluted magnetic semiconductor quantum wells with laser driving are derived. The model includes the magnetic as well as the nonmagnetic carrier-impurity interaction, the Coulomb interaction, Zeeman terms, and the light-matter coupling, allowing for an explicit treatment of arbitrary excitation pulses. Based on a dynamics-controlled truncation scheme, contributions to the equations of motion up to second order in the generating laser field are taken into account. The correlations between the carrier and the impurity subsystems are treated within the framework of a correlation expansion. For vanishing magnetic field, the Markov limit of the quantum kinetic equations formulated in the exciton basis agrees with existing theories based on Fermi's golden rule. For narrow quantum wells excited at the $1s$ exciton resonance, numerical quantum kinetic simulations reveal pronounced deviations from the Markovian behavior. In particular, the spin decays initially with approximately half the Markovian rate and a non-monotonic decay in the form of an overshoot of up to $10\%$ of the initial spin polarization is predicted.

17 pages, 3 figures, typographical errors corrected (Erratum published in Phys. Rev. B 96, 239904)

References in corpus (6)

• Theory of ferromagnetic (III,Mn)V semiconductors
• Ultrafast demagnetization in the sp-d model: a theoretical study
• Electron spin relaxation in paramagnetic Ga(Mn)As quantum wells
• Unified picture for diluted magnetic semiconductors
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Cited by in corpus (8)

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• Many-body correlations brought to light in absorption spectra of diluted magnetic semiconductors
• Spin dynamics of hot excitons in diluted magnetic semiconductors with spin-orbit interaction
• Phonon impact on the dynamics of resonantly excited and hot excitons in diluted magnetic semiconductors
• Understanding and utilizing the inner bonds of process tensors
• Role of excited states in the dynamics of excitons and their spins in diluted magnetic semiconductors
• Origins of overshoots in the exciton spin dynamics in semiconductors