Spin-polarization spectroscopy in rectangular GaAs quantum wires

We measured spin-polarized photoluminescence excitation spectra and spin-re laxation times in rectangular GaAs/AlAs quantum wires (QWRs) with small (<2 0 nm) lateral sizes. We found that the degree of spin polarization had its maximum value near the transition edge, and varied greatly with the excitat ion photon energy. The results agreed qualitatively with theoretically anal yzed spin-polarization spectra, where the heavy-hole-light-hole mixing stat es in the one-dimensional (1D) valence subbands were taken into account. To clarify the effects of 1D confinement on the spin-relaxation process, we a lso investigated the temperature dependence of the spin-relaxation time in the QWRs. A comparison of the QWR and quantum-well spin-relaxation times re vealed that the spin-relaxation rate is reduced in 1D structures in the low -temperature region of 15-80 K. [S0163-1829(98)01148-5].