title: Coulomb excitations of monolayer germanene.
abstract: The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbit coupling and the buckled structure. The collective and single-particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e-h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e-h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.
authors.affiliation: Department of Physics, National Cheng Kung University, Taiwan.
authors.forename: Po-Hsin
authors.initials: PH
authors.lastname: Shih
authors.affiliation: Department of Applied Physics, National Pingtung University, Pingtung, Taiwan.
authors.forename: Yu-Huang
authors.initials: YH
authors.lastname: Chiu
authors.affiliation: Center for General Education, National Kaohsiung Marine University, Kaohsiung, Taiwan.
authors.forename: Jhao-Ying
authors.initials: JY
authors.lastname: Wu
authors.affiliation: Department of Physics, Republic of China Military Academy, Kaohsiung, Taiwan.
authors.forename: Feng-Lin
authors.initials: FL
authors.lastname: Shyu
authors.affiliation: Department of Physics, National Cheng Kung University, Taiwan.|National Center for Theoretical Sciences (south), Taiwan.
authors.forename: Ming-Fa
authors.initials: MF
authors.lastname: Lin