Collective modes of a bilayer quasi-two-dimensional spin polarized electron gas

In the presence of a weak electromagnetic perturbation, it is shown that a bilayer quasi-two-dimensional spin polarized system exhibits coupled in-phase and out-of-phase charge and spin density resonant excitations. These modes occur when either the self-consistent magnetization or Coulomb interaction effects beyond the random phase approximation are considered. The latter are introduced by means of spin-dependent local field corrections for exchange (x) and correlation (c), G(sigma)(x(c))((q) over right arrow ,w). We analyze both intra- and inter-subband excitations and provide analytic results for their excitation frequencies in the long wavelength limit. (C) 2002 Published by Elsevier Science B.V.