Possible Realization of Hyperbolic Plasmons in Few-Layered Rhenium Disulfide

Hyperbolic plasmons are a highly desired property in optoelectronics and biomolecular sensing. The necessary condition to realize hyperbolic plasmons is a significant anisotropy of the principal components of the dielectric function, such that at a certain frequency range, one component is negative and the other is positive, i.e., one component is metallic, and the other one is dielectric. Here, we study the effect of anisotropy in ReS2, and our theory shows that ReS2 can host hyperbolic plasmons in the ultraviolet frequency range. The operating frequency range of the hyperbolic plasmons can be tuned with the number of ReS2 layers. However, we note that the significantly large imaginary part of the macroscopic dielectric response in all layered variants of ReS2 can result in substantial losses for the hyperbolic plasmons, as in the case with other known hyperbolic materials, with the exception of MoOCl2. We also note that ReS2 hosts ultraviolet hyperbolic plasmons while ZrSiSe, WTe2, and CuS nanocrystals host infrared plasmons, providing a novel platform for optoelectronics in the ultraviolet range.