Plasmons in bilayer graphene with O-type Kekulé distortion: Electron-hole asymmetry of the effective interlayer tunneling

The effective interlayer tunneling (EIT) is a key quantity in determining the out-of-phase plasmons of a bilayer structure. Using the tight-binding model and the random phase approximation, we investigate plasmons in bilayer graphene with O-type Kekulé distortion. Both O/O and G/O bilayers exhibit strong electron-hole asymmetry in the EIT. For the O/O bilayer, the gap of the out-of-phase plasmon remains almost constant as the electron concentration varies, whereas it increases rapidly with increasing hole concentration; hole doping can also lead to stronger anomalous dispersion than electron doping. For the G/O bilayer, enhancing the Kekulé distortion $Δ_0$ can weaken the EIT, as reflected by the reduced interlayer hybridization caused by the lifted layer degeneracy, especially for the electron-doped case. For the electron-doped G/O bilayer, the EIT is almost turned off when $Δ_0=0.3$ from the perspective of the dispersion. Our results imply that switching the doping type between electron and hole can tune the performance of out-of-phase plasmon-based devices by modulating the EIT.