| Popis: |
We study the coupling between plasmon modes by the long-range Coulomb electron–electron interaction for a system consisting of a two-dimensional system of Dirac electrons embedded in three-dimensional Dirac semimetal for various separations of the subsystems. The plasmon mode in the three-dimensional Dirac semimetal has the optic dispersion, while the plasmon mode in the two-dimensional system of Dirac electrons has the characteristic acoustic square-root dependence on the momentum. The mixing of the plasmon modes is achieved as the two-dimensional acoustic plasmon mode dispersion crosses the bulk plasmon mode. We find that the upper coupled plasmon mode increases from the bulk plasmon mode as the momentum increases and tends to the bare two-dimensional plasmon at large momenta, while at the same time the lower coupled plasmon mode increases linearly from zero as the momentum increases and approaches the bare bulk plasmon mode at large momenta. The coupled plasmon modes become more separated with decreasing the separation between two subsystems as the coupling increases due to the enhanced Coulomb interaction between electrons from different subsystems. We also demonstrate how the coupling affects the spectral weights of the obtained modes in two subsystems for different separations. In addition, we study the effects of the Dirac cones tilts on coupled plasmon modes in both subsystems. We show that the tilts of Dirac cones anisotropically increase the coupled plasmon mode energies and renormalize their spectral weights. The anisotropic effects of the tilt are more significant for larger separations of the subsystems. |
