Spin energetics in a GaAs quantum well: Asymmetric spin-flip Raman scattering

We demonstrate an asymmetric dependence of the spin-flip electronic Raman s pectrum from a two-dimensional electron gas on the direction of circular po larization of the photons, resulting from an interference of light scattere d from longitudinal and transverse spin-density fluctuations. By exploiting these selection rules, we are able to determine experimentally that the si gn of the band-structure parameter a(42), which describes the bulk k(3) con duction-band spin splitting in zinc-blende semiconductors, is negative for GaAs. [S0163-1829(99)50504-3].