Motivated by recent demands of the nanoplasmonic community, quasi-one-dimensional nanoribbons have attracted significant attention as promising materials in logic applications. By using the linear response theory and the Green's function formulation, we demonstrate how external local perturbations affect both intra- and interband plasmons in semiconductor armchair nanoribbons (aNRs). To do so practically, we focus on the silicon carbide aNRs subjected to a test photon beam. Particularly, the interplay between intra- and interband charge-density excitations is compared by taking into account the impact of ribbon width, the electronic dopant, the Zeeman magnetic field, temperature, and the incident photon wave vector on the dielectric function qualitatively. Furthermore, the combined effect of both weak and strong perturbations is studied. We show that both the intraband and interband plasmon excitations have a high susceptibility to perturbations, leading to the different optical features of the system. Moreover, we found various perturbation-dependent threshold frequencies in which the undamped plasmon modes and plasmon resonances take place. Finally, the invalidity of the linear response theory at strong perturbations is discussed concisely. Generically, the propagation and confinement of plasmon modes in the presence of weak and strong perturbations are reported. Our findings are useful for experimentalists to tune the optical properties of low-dimensional materials by perturbations.

• Received 13 July 2018
• Revised 5 September 2018

DOI:https://doi.org/10.1103/PhysRevB.98.155424