Temperature and inhomogeneity combination effects on collective excitations in three-layer graphene structures

Abstract

Temperature and the inhomogeneity of background dielectric combination effects on the collective excitations in a multilayer graphene structure consisting of three monolayer graphene sheets are investigated, within the random-phase approximation. Numerical calculations present that three weakly damped plasmon modes exist and continue in inter single-particle excitation region. Our investigations show that as temperature increases, the acoustic plasmon frequencies slightly decrease and then increase after getting the lowest peak. Dissimilarly, the optical plasmon frequency increases with the increasing temperature in the large wave vector regions. Besides, temperature effects cause the energy loss to plasmon modes even nearby the Dirac points, outside the single-particle excitation region of the system. We also observe that the inhomogeneity of background dielectric declines the plasmon energy, the damping rate of plasma oscillations , and the effects of temperature and interlayer separation on the collective excitations in the system. • Three plasmon modes exist and continue in SPE region of the system. • Acoustic modes decrease and then increase with increasing temperature. • Optical mode increases as temperature increases. • Temperature causes the energy loss to plasmon modes outside the SPE region. • The inhomogeneity declines the plasmon energy, the damping rate and the effects of temperature and separation on the collective excitations.