Mingwen Zhao1
Shandong University1
Hyperbolic materials (HMs) have garnered significant interest for their unique electromagnetic response characteristics, including optical nanoscale cavities, spontaneous emission enhancement, nanoscale imaging, and full-angle negative refraction. While initially achieved in metamaterials, the development of meta hyperbolic surfaces through intricate substrate patterning has enabled the support of highly-directional hyperbolic surface plasmons, crucial for optoelectronic devices. In this study, we introduce the concept of hyperbolicity into natural two-dimensional (2D) materials exhibiting highly-anisotropic electronic band structures. We demonstrate that these materials present intriguing scenarios similar to those observed in meta hyperbolic surfaces. Notably, natural hyperbolic 2D materials possess advantages over meta-surfaces, leveraging their small atomic-scale periodicity to yield large wavevectors and easy predictability without the need for complicated surface patterning. Based on orbital anisotropy, we propose a design principle for 2D hyperbolic materials and predict a family of candidate materials using first-principles calculations. Our computational results showcase the broadband hyperbolic regimes exhibited by these natural 2D-HMs across the near-infrared to ultraviolet spectrum, enabling the propagation of highly directional hyperbolic surface plasmons. By simulating the directional propagation of surface waves with hyperbolic dispersion relations through the solution of Maxwell’s equations, we establish a correlation between the fascinating plasmonic properties and the unique electronic structures of these highly-anisotropic 2D materials. The findings presented in this study offer a promising strategy for the design of 2D hyperbolic materials, paving the way for advancements in optoelectronic devices and expanding the possibilities of utilizing natural materials with remarkable electromagnetic characteristics.