Spectral weights of mixed coupled plasmon modes in Dirac electron systems with different dimensionality

Abstract

Abstract We study the effects of coupling between plasmon modes by the long-range Coulomb electron–electron interaction for a system consisting of a two-dimensional (2D) system of Dirac electrons embedded in three-dimensional (3D) Dirac semimetal. We obtain the dispersions of coupled plasmon modes for various separations of the subsystems. The coupled 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 the 2D subsystem both coupled modes have finite weights for small wave numbers, while for large wave numbers only the upper mode persists. On the other hand, in the bulk this mode takes most of the spectral weight for small wave numbers, while for large wave numbers the lower mode is more pronounced.