Origins of overshoots in the exciton spin dynamics in semiconductors

Abstract

We investigate the origin of overshoots in the exciton spin dynamics after resonant optical excitation. As a material system, we focus on diluted magnetic semiconductor quantum wells as they provide a strong spin-flip scattering for the carriers. Our study shows that overshoots can appear as a consequence of radiative decay even on the single-particle level in a theory without any memory. The magnitude of the overshoots in this case depends strongly on the temperature as well as the doping fraction of the material. If many-body effects beyond the single-particle level become important so that a quantum-kinetic description is required, a spin overshoot appears already without radiative decay and is much more robust against variations of system parameters. We show that the origin of the spin overshoot can be determined either via its temperature dependence or via its behavior for different doping fractions. The results can be expected to apply to a wide range of semiconductors as long as radiative decay and a spin-flip mechanism are present.

arXiv comment9 pages, 6 figures

References in corpus (18)

• Spintronics: Fundamentals and applications
• Ferromagnetism in semiconductors and oxides: prospects from a ten years' perspective
• Dilute ferromagnetic semiconductors: Physics and spintronic structures
• Spin dynamics in semiconductors
• Ultrafast demagnetization in the sp-d model: a theoretical study
• Electron correlations in Mn${}_x$Ga${}_{1-x}$As as seen by resonant electron spectroscopy and dynamical mean field theory
• Damping of Rabi oscillations in intensity-dependent photon echoes from exciton complexes in a CdTe/(Cd,Mg)Te single quantum well
• Non-Markovian spin transfer dynamics in magnetic semiconductors despite short memory times
• Influence of non-magnetic impurity scattering on the spin dynamics in diluted magnetic semiconductors
• Ultrafast spin dynamics in II-VI diluted magnetic semiconductors with spin-orbit interaction
• Quantum kinetic equations for the ultrafast spin dynamics of excitons in diluted magnetic semiconductor quantum wells after optical excitation
• Trend reversal in the magnetic-field dependence of exciton spin-transfer rates in diluted magnetic semiconductors due to non-Markovian dynamics
• Non-Markovian Effects in the Spin Transfer Dynamics in Diluted Magnetic Semiconductors due to Excitation in Proximity to the Band Edge
• Non-perturbative Correlation Effects in Diluted Magnetic Semiconductors
• Nonexponential spin decay in a quantum kinetic description of the D'yakonov-Perel' mechanism mediated by impurity scattering
• Many-body correlations brought to light in absorption spectra of diluted magnetic semiconductors
• Phonon-induced quantum ratchet in the exciton spin dynamics in diluted magnetic semiconductors in a magnetic field
• Phonon impact on the dynamics of resonantly excited and hot excitons in diluted magnetic semiconductors