Wake effect in interactions of ions with graphene-sapphire-graphene composite system

Abstract

We study the wake effect in a graphene-Al 2 O 3 -graphene composite system induced by an external charged particle moving parallel to it by using the dynamic polarization function of graphene within the random phase approximation for its π electrons described as Dirac's fermions and by using a local dielectric function for the bulk sapphire (aluminum oxide, Al 2 O 3 ). We explore the effects of variation of the particle speed, its distance from the top graphene layer, the thickness of the Al 2 O 3 layer, the damping rate of plasmons in graphene, and the doping density (i.e., Fermi energy) of graphene on the wake potential. For the velocity of the charged particle below the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity v F , strong effects are observed due to variation of the particle distance, while for the velocity of the charged particle above v F strong effects are observed due to varying the thickness of the Al 2 O 3 layer, as well as due to plasmon damping of graphene's π electrons, and graphene doping. • We present the wake effect in graphene-Al 2 O 3 -graphene due to moving charge particle. • Particle velocity v is taken to be below and above Fermi velocity in graphene v F . • For v < v F wake is dominated by Fuchs-Kliewer phonons regardless of the Al 2 O 3 thickness. • Fuchs-Kliewer phonons are weakened by Landau damping as doping of graphene increases. • For v F < v < 3 v F wake is dominated by hybridization of Dirac plasmons in graphene layers.