OBSERVATION OF MANY-BODY INTERACTIONS OF ELECTRONS IN COUPLED DOUBLE-QUANTUM WELLS

We have investigated, by resonant inelastic light-scattering, the fini te in-plane wavevector dispersion of the collective excitations of ele ctron bilayers in AlGaAs/GaAs double quantum wells. As the wavevector is increased the plasmon mode first becomes Landau damped and then at larger wavevectors it re-appears as it emerges from one of the two max ima of the continuum of single-particle excitations in a two-dimension al system with two occupied subbands. These measurements enable quanti tative determination of many-body interactions in dilute electron bi-l ayers.