Title: Magnetic polarons in a nonequilibrium polariton condensate,
Abstract: We consider a condensate of exciton-polaritons in a diluted magnetic
semiconductor microcavity. Such system may exhibit magnetic self-trapping in
the case of sufficiently strong coupling between polaritons and magnetic ions
embedded in the semiconductor. We investigate the effect of the nonequilibrium
nature of exciton-polaritons on the physics of the resulting self-trapped
magnetic polarons. We find that multiple polarons can exist at the same time,
and derive a critical condition for self-trapping which is different to the one
predicted previously in the equilibrium case. Using the Bogoliubov-de Gennes
approximation, we calculate the excitation spectrum and provide a physical
explanation in terms of the effective magnetic attraction between polaritons,
mediated by the ion subsystem.