Plasmon modes in double-layer gapped graphene

We calculate plasmon frequencies and decay rates of plasma oscillations in double layer gapped graphene (DLGG) made of two parallel monolayer gapped graphene sheets, separated by a dielectric spacer. The results are compared to those in double layer gapless graphene with the same parameters. Numerical calculations show that, as in other double-layer systems, two plasmon modes exist in DLGG, corresponding to in-phase and out-of-phase oscillations of carriers in two sheets of the system. The energy loss of acoustic plasmon mode in DLGG is remarkably different from that in DLG caused by a separation of intra- and inter-band single-particle excitation regions of DLGG. In addition, the increase in band gap leads to a significant decrease in DLGG plasmon frequencies. Finally, the temperature dependence of plasmon properties in DLGG differs remarkably from that in DLG, and the effect of the band gap on plasmon characters decreases notably with increasing temperature.