Emerging Dirac materials for THz plasmonics

Terahertz (THz) photonics is a key-enabling technology for a wealth of urgently demanding applications and societal challenges like ultrahigh speed communication systems, medical imaging and diagnostics, industrial and food quality control, and security screening. Therefore, making novel THz materials, that are able to effectively interact and manipulate THz radiation, is a challenge in this respect. Dirac materials that are endowed with linearly dispersed electronic bands, are a promising frontier in this framework as they are suited to generate plasmon resonances in the THz regime. Dirac materials include the well-known cases of graphene and three dimensional topological insulators. In perspective they can be extended to new emerging materials including graphene-like Xenes (from silicene to bismuthene) and Weyl/Dirac semimetals. In addition to the materials aspects, in this perspective review we deliberately single out an easy framework where to validate Dirac materials for THz applications. This one includes the optical conductivity deduced by THz spectroscopy as a good figure of merit, and the micro-ribbon pattern as a good plasmonic grating. In the end, we outline future challenges and current bottlenecks in the production and exploitation of Dirac materials in the THz technology.