Electron-exciton interactions in the exciton-polaron problem

Abstract

Recently, it has been demonstrated that the absorption of moderately doped two-dimensional semiconductors can be described in terms of exciton-polarons. In this scenario, attractive and repulsive polaron branches are formed due to interactions between a photo-excited exciton and a Fermi sea of excess charge carriers. These interactions have previously been treated in a phenomenological manner. Here, we present a microscopic derivation of the electron-exciton interactions which utilizes a mixture of variational and perturbative approaches. We find that the interactions feature classical charge-dipole behavior in the long-range limit, and that they are only weakly modified for moderate doping. We apply our theory to the absorption properties and show that the dependence on doping is well captured by a model with a phenomenological contact potential.

Polaritons in an electron gas -- quasiparticles and Landau effective interactions

“…The large binding energy of excitons in TMDs as compared to other microcavity semiconductors like quantumwells [32][33][34], combined with the possibility to control the electron density in the different valleys, opens up exciting new venues to explore Bose-Fermi mixtures in a hybrid light-matter setting [35][36][37]. This has stimulated a number of studies regarding the properties electron-exciton mixtures and their coupling to light [38][39][40][41][42][43][44][45][46][47][48]. In particular, the emergence of new quasiparticles, the so-called Fermi-polaron-polaritons have been observed [49].…”