Collective spin-density excitations in a III-V semiconductor quantum well

We study the spin-density excitations in a III-V semiconductor quantum well, where the single-particle energies are spin split due to the spin-orbit coupling. The vertex corrections to the polarizability are treated within a Fermi-liquid scheme. It is found that the vertex corrections cause the appearance of one longitudinal and two transverse collective spin-density excitation modes with frequencies red shifted with respect to the single-particle spin splitting. The calculated Raman spectrum shows strong angular and polarization dependence of the collective and single-particle Raman peaks due to interference of the spinor amplitudes.