Surface Response, Plasma Modes of coated Multi-Layered anisotropic Semi-Dirac Heterostructures

TL;DR

This paper derives analytical expressions for surface response functions in layered heterostructures of 2D materials, analyzing plasmonic properties and anisotropic behaviors with potential applications in protective coatings.

Contribution

It provides new closed-form formulas for surface response functions and plasmon dispersions in layered semi-Dirac heterostructures, revising previous models.

Findings

Analytical expressions for plasmon dispersions in long wavelength limit.

Observation of anisotropic loss function behavior in different directions.

Identification of two plasmon branches in multilayer structures.

Abstract

We derived closed-form analytical expressions for the surface response functions (SRFs) for heterostructure. We investigate structures consisting of up to three layered, coated heterostructure of two-dimensional (2D) materials with a dielectric medium or vacuum interface. The dielectric media serves to inhibit charge transfer between layers for the case when a pair of 2D layers serve as coatings for a dielectric film. Our results revise the established picture for the dispersion equation for two layers of reduced dimensionality surrounded by dielectric media. An impinging electromagnetic field incident on the surface leads to Coulomb coupled plasma excitations in the structure which are yielded by the SRF. This is achieved by employing Maxwell's equations and linear response theory. We use these results to investigate the plasmonic properties of tilted semi-Dirac materials both analytically and numerically. Closed-form analytical expressions are derived for the plasmon dispersions in the long wavelength limit for single and double layers. We numerically obtain density plots of the loss functions and observe anisotropic behavior in different momentum directions. For the cases when there are two or three layers, we observe two plasmon branches corresponding to in-phase and out-of-phase charge density oscillations, where the in-phase optical modes have higher intensity than the out-of-phase acoustic modes. We calculated the optical absorption spectra for plasma modes in layered semi-Dirac materials produced by an external electromagnetic field carrying an electric polarization and frequency. Possible applications include durable protection coatings providing UV resistance, chemical protection and improving upon traditional ceramic coatings.