Excitation of plasmon wakes in two-dimensional electron systems by moving external charged particles

Abstract

We use the dielectric response formalism to explore the wake effect due to excitation of the sheet plasmons in graphene and in a two-dimensional (2D) electron gas with a parabolic energy band, caused by an externally moving charged particle. Using the random phase approximation to obtain the relevant polarisation functions, we have found similarities as well as some differences in the V-shaped wake patterns that result from different structures of the single-particle excitation spectra in those two electron systems. While both systems exhibit a velocity threshold for the charged particle to be able to excite a wake, graphene shows some irregularities in the wake oscillations behind that particle, whereas the 2D electron gas exhibits a larger opening angle of its V-shaped wake.