Plasmon modes in three-layer graphene with inhomogeneous background dielectric

Abstract

The aim of this paper is to investigate collective excitations and the damping rate in a multilayer structure consisting of three monolayer graphene sheets with inhomogeneous background dielectric at zero temperature within random-phase approximation. Numerical results show that one optical branch and two acoustic ones exist in the system. The lowest frequency branch disappears as touching single-particle excitation area boundary while two higher frequency branches continue in this region. Calculations also illustrate that the frequency of optical (acoustic) mode(s) decreases (increase) as interlayer separation increases. The inhomogeneity of background dielectric and the imbalance in the carrier density in graphene sheets decline significantly plasmon frequencies in the system. Therefore, it is meaningful to take into account the effects of inhomogeneous background dielectric when calculating collective excitations in three-layer graphene structures.