Terahertz and Infrared Plasmon Polaritons in PtTe 2 Type-II Dirac Topological Semimetal.

Surface plasmon polaritons (SPPs) are electromagnetic excitations existing at the interface between a metal and a dielectric. SPPs provide a promising path in nanophotonic devices for light manipulation at the micro and nanoscale with applications in optoelectronics, biomedicine, and energy harvesting. Recently, SPPs have been extended to unconventional materials like graphene, transparent oxides, superconductors, and topological systems characterized by linearly dispersive electronic bands. In this case, three-dimensional Dirac and Weyl semimetals offer a promising frontier for infrared (IR) and terahertz (THz) radiation tuning by topologically-protected SPPs. In this work, we investigate the THz-IR optical response, of platinum ditelluride (PtTe 2 ) type-II Dirac topological semimetal films grown on Si substrates. We detect SPPs generated on microscale ribbon arrays of PtTe 2  in the far-field limit, finding an excellent agreement among measurements, theoretical model, and electromagnetic simulation data. The far-field measurements have been further supported by near-field infrared data which indicate a strong electric field enhancement due to the SPP excitation near the ribbon edges. The whole results of this paper, indicate that PtTe 2  ribbon array appears an ideal active layout for geometrically tunable SPPs thus inspiring a new fashion of optically tunable materials in the technologically demanding THz and IR spectrum. This article is protected by copyright. All rights reserved.