Zero-magnetic-field spin splitting in the GaAs conduction band from Raman scattering on modulation-doped quantum wells

We present Raman scattering spectra of intrasubband excitations in an n-type modulation-doped single quantum well. We attribute a double peak in the depolarized spectra to be due to spin-flip single-particle transitions. This gives direct spectroscopic evidence at zero applied magnetic field of the spin splitting of the conduction band of GaAs due to the lack of inversion symmetry in zinc-blende compounds.