Quantum oscillations of spin polarization in a GaAs/AlGaAs double quantum well

Abstract

We employ the circular polarization-resolved magneto-photoluminescence technique to probe the spin character of electron and hole states in a GaAs/AlGaAs strongly coupled double quantum well system. The photoluminescence intensities of the lines associated with symmetric and antisymmetric electron states present clear out-of-phase oscillations between integer values of the filling factor ν and are caused by magnetic field induced changes in the population of occupied Landau levels near to the Fermi level of the system. Moreover, the degree of circular polarization of these emissions also exhibits the oscillatory behavior with increasing magnetic field. Both quantum oscillations observed in the PL intensities and in the degree of polarizations may be understood in terms of a simple single-particle approach model. The k · p method was used to calculate the photoluminescence peak energies and the degree of circular polarizations in the double quantum well structure as a function of the magnetic field. These calculations prove that the character of valence band states plays an important role in the determination of the degree of circular polarization and, thus, resulting in a magnetic field induced change of the polarization sign.

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

“…Figures 3(c) and (d) present, respectively, the odd parity °Pz (solid green curves) and the even parity P z e (dashed orange curves) for states A and B of the valence band when θ = °0 . Such results show that spin character and even parity are well defined for states A and B when θ = °0 , as already observed in [5,22]. In fact, state A is a pure spin-down HH state ⟩ ⟩ ( )…”

Strain and localization effects in InGaAs(N) quantum wells: Tuning the magnetic response

“…The first phenomenon has been reported for some systems 36 and it is under investigation, while the second one can be attributed to the spin dynamics during carrier relaxation at the conduction band. 37 We have observed that the polarization degrees for the N-2containing samples are slightly higher than for N-free samples and the spin-dependent effects are stronger for wider QWs for both systems. Remark that under higher magnetic fields, the spin polarization degree remains within the range of [À20, À10%], regardless of the structural parameters of the QW.…”

Spectroscopic evidence of quantum Hall interlayer tunneling gap collapse caused by tilted magnetic field in a GaAs/AlGaAs triple quantum well

“…Therefore, they cannot be attributed to the magnetic-field-induced variations in the occupied density of states of the Landau levels nearest the Fermi energy as detected in Ref. [45]. We assign the PL intensity maxima found in the tilted magnetic field to the collapses of the tunneling gaps shown in the magnetoresistance plot by open gray circles.…”