Plasmon modes of double-layer graphene at finite temperature

• We investigate the temperature effects on the plasmon dispersion mode and loss function of doped double-layer graphene.
• The temperature acoustic mode ω−ω− in the case of n2=0 is degenerate with the ω=υFqω=υFq line only when d→0d→0.
• Even though n2=0, when d→0d→0 the temperature optical mode ω+ω+ does not become the single-layer plasmon with the same density.
• The effect of temperature on the plasmon dispersion and damping is significant.

We calculate the dynamical dielectric function of doped double-layer graphene (DLG), made of two parallel graphene monolayers with carrier densities n1 and n2, and an interlayer separation of d at finite temperature. The results are used to find the dispersion of plasmon modes and loss functions of DLG for several interlayer separations and layer densities. We show that in the case of n2=0, the finite-temperature plasmon modes are dramatically different from the zero-temperature ones.