Spin-dependent electron many-body effects in GaAs

Abstract

Time-and polarization-resolved differential transmission measurements employing same and oppositely circularly polarized 150 fs optical pulses are used to investigate spin characteristics of conduction band electrons in bulk GaAs at 295 K. Electrons and holes with densities in the 2 ϫ 10 16 cm −3-10 18 cm −3 range are generated and probed with pulses whose center wavelength is between 865 and 775 nm. The transmissivity results can be explained in terms of the spin sensitivity of both phase-space filling and many-body effects ͑band-gap renormalization and screening of the Coulomb enhancement factor͒. For excitation and probing at 865 nm, just above the band-gap edge, the transmissivity changes mainly reflect spin-dependent phase-space filling which is dominated by the electron Fermi factors. However, for 775 nm probing, the influence of many-body effects on the induced transmission change are comparable with those from reduced phase space filling, exposing the spin dependence of the many-body effects. If one does not take account of these spindependent effects one can misinterpret both the magnitude and time evolution of the electron spin polarization. For suitable measurements we find that the electron spin relaxation time is 130 ps.

Fast Optical Control of Spin in Semiconductor Interfacial Structures

“…In the bare GaAs substrate and the undoped epitaxial GaAs on the substrate, the spin lifetimes are more than 2 orders of magnitudes shorter-350 and 70 ps for the substrate and epitaxial GaAs, respectively. This agrees well with the observed τ in the sample with the barrier and with typical values reported for undoped bulk GaAs, where the spin lifetime of spin-polarized photocarriers is limited by their recombination time and where τ is typically reported at the time scale of hundreds of picoseconds [10,13,20]. The inferred g factors are the same within the experimental error for all three samples.…”

Spin dynamics in semiconductors

“…It has long been believed in the literature that the Bir-Aronov-Pikus mechanism is dominant at low temperature in ptype samples and has important contribution to intrinsic samples with high photo-excitation [574,[687][688][689]693,856,857]. 77 Instead of T * 2 which is measured from the Faraday/Kerr rotation experiment.…”

Pauli blockade of the electron spin flip in bulk GaAs

“…19 and 6); and (ii) localization centers that are critical in the determination of the spin-relaxation mechanism. 6,11,12 Another fundamental issue that has not been explored until very recently, is the physics of spin-dependent electron many-body processes [20][21][22] and phase-space filling effects. 23,24 Due to the difficulties in the theoretical modeling and in the analysis of the experimental results, the spin relaxation mechanisms in the regime where these effects are important are not well known.…”