Study of collective excitations in monolayer-bilayer graphene heterostructures: Temperature effects

In this paper, we study collective excitations in an M-BLG heterostructure, consisting of one BLG and one parallel MLG sheet on an inhomogeneous background dielectric. Theoretical calculations are carried out within the random-phase approximation, taking into account temperature effects. The results illustrate that two solutions, corresponding to optical and acoustical modes, admit the zero equation of the temperature-dependent dynamical dielectric function of the structure. The energy of these collective modes is significantly larger (smaller) than that in DBLG (DLG) systems with similar parameters. As temperature increases, the frequency of the acoustical mode steadily increases while that of the optical mode only increases in large wave vector regions, found differently with different interlayer separations. Interestingly, we explore that the effects of carrier density in graphene on plasmon properties of M-BLG heterostructures sharply differ from those in both BLG and DLG systems. •Two plasmon modes, corresponding to optical and acoustical modes, are found.•Plasmon frequencies are significantly larger (smaller) than that in DBLG (DLG).•The AC mode frequency steadily with increasing temperature.•The OP mode frequency increases in small wave vector regions.•Carrier density causes different effects on plasmon properties of M-BLG heterostructures.