Optical Spin Orientation under Inter- and Intra-Subband Transitions in QWs

The degree and orientation of the magnetic-field induced linear polarization of the photoluminescence from a wide range of heterostructures containing (Cd,Mn)Te quantum wells between (Cd,Mn,Mg)Te barriers has been studied as a function of detection photon energy, applied magnetic field strength and orientation in the quantum well plane. A theoretical description of this effect in terms of an in-plane deformation acting on the valence band states is presented and is verified b...

We present a theory that describes the appearance of circular polarization of the photoluminescence (PL) in ferromagnet-semiconductor hybrid heterostructures due to spin-dependent tunneling of photoexcited carriers from a quantum well into a magnetic layer. The theory succeeds in explaining the experimental data on time-resolved PL for heterostructures consisting of InGaAs-based quantum well (QW) and a spatially separated Mn $\delta$-layer. We show that the circular polarizat...

The theory of spin relaxation of conduction electrons is developed for zinc-blende-type quantum wells grown on (110)-oriented substrate. It is shown that, in asymmetric structures, the relaxation of electron spin initially oriented along the growth direction is characterized by two different lifetimes and leads to the appearance of an in-plane spin component. The magnitude and sign of the in-plane component are determined by the structure inversion asymmetry of the quantum we...

The flow of electric current in quantum well breaks the space inversion symmetry, which leads to the dependence of the radiation transmission on the relative orientation of current and photon wave vector, this phenomenon can be named current drag of photons. We have developed a microscopic theory of such an effect for intersubband transitions in quantum wells taking into account both depolarization and exchange-correlation effects. It is shown that the effect of the current d...

We report on the observation of photogalvanic effects induced by terahertz radiation in type-II GaSb/InAs quantum wells with inverted band order. Photocurrents are excited at oblique incidence of radiation and consists of several contributions varying differently with the change of the radiation polarization state; the one driven by the helicity and the other one driven by the linearly polarization of radiation are of comparable magnitudes. Experimental and theoretical analys...

We have observed a large spin splitting between "spin" $+1$ and $-1$ heavy-hole excitons, having unbalanced populations, in undoped GaAs/AlAs quantum wells in the absence of any external magnetic field. Time-resolved photoluminescence spectroscopy, under excitation with circularly polarized light, reveals that, for high excitonic density and short times after the pulsed excitation, the emission from majority excitons lies above that of minority ones. The amount of the splitti...

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 den...

In this work we investigated the InAs/InAlAs quantum wires (QWRs) superlattice by optically exciting the structure with near-infrared radiation. By varying the helicity of the radiation at room temperature we observed the circular photogalvanic effect related to the $C_{2v}$ symmetry of the structure, which could be attributed to the formation of a quasi two-dimensional system underlying in the vicinity of the QWRs pattern. The ratio of Rashba and Dresselhaus terms shows an e...

We calculate circularly polarized luminescence emitted parallel (vertical emission) and perpendicular (edge emission) to the growth direction from a quantum well in a spin light-emitting diode (spin-LED) when either the holes or electrons are spin polarized. It is essential to account for the orbital coherence of the spin-polarized holes when they are captured in the quantum well to understand recent experiments demonstrating polarized edge emission from hole spin injection. ...

We report on the observation of the circular (helicity-dependent) and linear photogalvanic effects in Si-MOSFETs with inversion channels. The developed microscopic theory demonstrates that the circular photogalvanic effect in Si structures it is of pure orbital nature originating from the quantum interference of different pathways contributing to the light absorption.