Diffusion of Photoexcited Holes in a Viscous Electron Fluid.

The diffusion of photogenerated holes is studied in a high-mobility mesoscopic GaAs channel where electrons exhibit hydrodynamic properties. It is shown that the injection of holes into such an electron system leads to the formation of a hydrodynamic three-component mixture consisting of electrons and photogenerated heavy and light holes. The obtained results are analyzed within the framework of ambipolar diffusion, which reveals characteristics of a viscous flow.

Shake-up effect in photoluminescence of integer quantum Hall system formed in InGaAs/InP quantum wells.

Polarization-resolved magneto-photoluminescence is studied in InGaAs/InP single quantum wells. In the range of the filling factor ν ≥ 4 the number of populated Landau levels contributing to the photoluminescence is found to be equal to the corresponding filling factor, while at ν ≤ 3 the number of emitting Landau levels is larger than the filling factor, which implies an occupancy of the Landau levels above the Fermi level. Such partial occupancy of the Landau levels with energies higher than the Fermi energy is due to shake-up processes caused by electron-electron interaction.

Excitonic spin-splitting in quantum wells with a tilted magnetic field.

This work aims to investigate the effects of magnetic field strength and direction on the electronic properties and optical response of GaAs/AlGaAs-based heterostructures. An investigation of the excitonic spin-splitting of a disordered multiple quantum well embedded in a wide parabolic quantum well is presented. The results for polarization-resolved photoluminescence show that the magnetic field dependencies of the excitonic spin-splitting and photoluminescence linewidth are crucially sensitive to magnetic field orientation.

Magnetic field driven interminiband charge transfer in InGaAs/InP superlattices.

The characteristic energies, occupancies and polarizations of the minibands formed by the Γ-Γ and Γ-Xz interlayer electon tunnelings in the InGaAs/InP superlattices are studied in the regime of the integer quantum Hall effect by polarization resolved photoluminescence. Accordingly, the magnetic field induced shrinkage of the interminiband gap, predicted by the theory, and as a consequence, the redistribution of charge over the superlattice minibands and the depolarization of the quantum Hall electron states are observed at odd filling factors. The response of the electrons residing in the InGaAs/InP superlattice minibands to the magnetic field is found very similar to the corresponding response of the electrons confined in the symmetric and anti-symmetric two-dimensional minibands of GaAs/AlGaAs double quantum wells.

Circularly polarized photoluminescence as a probe of density of states in GaAs/AlGaAs quantum Hall bilayers.

Polarized magnetophotoluminescence is employed to study the energies and occupancies of four lowest Landau levels in a couple quantum Hall GaAs/AlGaAs double quantum well. As a result, a magnetic field-induced redistribution of charge over the Landau levels manifesting to the continuous formation of the charge density wave and direct evidence for the symmetric-antisymmetric gap shrinkage at ν=3 are found. The observed interlayer charge exchange causes depolarization of the ferromagnetic ground state.