Temperature effects on plasmon modes in double-bilayer graphene structures

Abstract

This paper aims to investigate collective excitations in a double-layer structure consisting of two parallel bilayer graphene sheets within random-phase-approximation. We determine the collective excitations in the system from the zeroes of the temperature-dependent dynamical dielectric function. Numerical results demonstrate that both optical in-phase and acoustic out-of-phase plasmon modes are found in the system, similar to other double-layer structures. Calculations prove that plasmon frequencies increase with the increase in temperature while the imbalance in doping density between two bilayer graphene sheets as well as the increase in carrier density decrease these frequencies. Similar to the case of zero temperature, increasing separation increases (decreases) acoustic (optical) plasmon frequency. Our computations illustrate that temperature affects remarkably and can reduce the effects of other factors on plasmon properties in double bilayer graphene systems.