Elementary excitations in spinor polariton-electron systems

We consider effective interactions in a two-dimensional (2D) hybrid polariton-electron system and calculate dispersion of elementary excitations by accounting for the spin degrees of freedom of the particles. Due to the crucial role played by the exchange term in polariton-electron interactions the dispersions of this system become spin dependent and show unusual behavior. The coupling of the excitations of the condensate with 2D plasmons can result in the appearance of roton minimum in the dispersion and destruction of the condensate for close enough situated quantum wells with electrons and excitons.