Large enhancement of polarization observed by extracted electrons from the AlGaAs-GaAs superlattice

We have observed a large enhancement of the spin polarization of electrons extracted from an AlGaAs-GaAs superlattice illuminated by circularly polarized light. A polarization of 71.2 \ifmmode\pm\else\textpm\fi{}1.1(stat)\ifmmode\pm\else\textpm\fi{}6.1(sys)% was obtained with a photon wavelength of 802 nm at room temperature. We have also confirmed the removal of the degeneracy between a heavy-hole band and a light-hole band at the \ensuremath{\Gamma} point from the laser-wavelength dependence of the polarization.