Coulomb drag of excitons in Bose-Fermi systems

Abstract

We develop a microscopic theory of the Coulomb drag effect in a hybrid system consisting of spatially separated two-dimensional quantum gases of degenerate electrons and dipolar excitons. We consider both the normal-phase and condensate regimes of the exciton subsystem and investigate the cross-mobility of the system being the kinetic coefficient, which couples the static electric field applied to the electron layer with the particle density current (flux) in the exciton subsystem. We study the temperature dependence of the cross-mobility and its dependence on the interlayer separation. We show that exciton-exciton interaction plays a dramatic role. If the exciton gas is in the normal phase, then the screening of interlayer interaction by the exciton subsystem results in an exponential damping of the cross-mobility with the decrease of temperature, while at low temperatures, the interactions result in a robust bosonic transport due to the emergence of the Bogoliubov quasiparticles. II. CROSS-MOBILITY OF AN EXCITON-ELECTRON SYSTEMWe consider a hybrid 2DEG-indirect exciton gas system (Fig. 1). The electron-exciton interaction results in the exciton flux, provided that an electric field is applied to the electronic layer. Within the linear response theory, the exciton flux J = n ex µ D E is proportional to the external (bias) electric field E, the density of exciton gas n ex , and the cross-mobility µ D , which we will concentrate on. arXiv:1902.09721v1 [cond-mat.mes-hall]

Superfluid drag between excitonic polaritons and superconducting electron gas

“…systems, where they provide the leading contribution, although in Bose-condensed systems they may be disregarded [29]. However, accounting for the noncondensate diagrams can be important in some cases, as argued, e.g., in Ref.…”

“…With the Green functions ( 14), similarly to [29], we write the lowest order contribution of the processes involving the condensate to the rectification function. It is proportional to the density of polariton condensate n p 0 :…”

Superfluid drag between excitonic polaritons and superconducting electron gas

“…, where g v is the valley degeneracy factor (1 for QW and 2 for TMDC electronic layer). Following a standard calculation based on the Matsubara technique [2], it can be shown that in a clean system or with uncorrelated disorder potentials in both layers the first order in the expansion of χ el−p ik over the interlayer electron-polariton interaction is zero in the static limit iω → 0, and the leading order is given by the second-order term [29]:…”

“…Modern two-dimensional materials and heterostructures [25,26] provide a prospective platform for realization of drag effects. Hybrid Bose-Fermi systems with polaronic and drag effects induced by electron-exciton and electron-polariton interactions are especially interesting in this context [27][28][29][30][31]. Formation of polaritons in semiconductor quantum wells and two-dimensional transition metal dichalcogenides embedded into optical microcavities [32] allows to enhance tunability of the Bose-Fermi systems, to increase the critical temperature of Bose-Einstein condensation (BEC) and to employ polaronic effects.…”

Light-induced topological superconductivity in transition metal dichalcogenide monolayers

“…Experiments have so far focused on the regime of small exciton concentration where their interaction with electrons leads to the formation of Fermi polarons [11-13, 16, 18, 19]. Increasing the exciton concentration beyond the polaron regime has been predicted to give rise to a range of intriguing phenomena such as trion liquids [20], density ordered, and superconducting phases [21][22][23][24][25][26][27].…”