Exchange-correlation effects and layer-thickness affect plasmon modes in gapped graphene-GaAs double-layer systems

We calculate collective excitations and damping rate in a double layer structure consisting of one monolayer gapped graphene sheet and a GaAs quantum well isolating two-dimensional electron gas within random-phase approximation at zero temperature. We observed that both in-phase optical and out-of-phase acoustic plasmon mode exist and can be un-damped in the system. The acoustic curve merges to single-particle excitation area boundary and disappear while the OP one crosses this border and continues in the region. Our analytical calculations present that the quantum well width has significant contribution only to acoustic mode in long wavelength limit. On the other hand, numerical results demonstrate that while both quantum well width and exchange-correlation effects decrease AC plasmon frequency, the OP one decreases with the increase in the band gap. Finally, taking into account local-field-correction in calculations leads to the decrease in only AC plasmon frequency, found mainly in large wave-vectors region.Graphic Abstract

Automated summary

In this study, we calculated collective excitations and damping rate in a double layer structure comprising one monolayer gapped graphene sheet and a GaAs quantum well using random-phase approximation at zero temperature. We found that both in-phase optical and out-of-phase acoustic plasmon modes exist in the system, with different responses to quantum well width and exchange-correlation effects. Taking into account local-field correction led to a decrease in only the AC plasmon frequency, mainly in the large wave-vectors region.