Unique Omnidirectional Negative Poisson's Ratio in δ-Phase Carbon Monochalcogenides

Auxetic materials (negative Poisson's ratio) are of exceptional importance for nanomechanical applications. Using first-principles calculations, we propose two-dimensional delta-phase carbon monochalcogenides (delta-CS, delta-CSe, and delta-CTe) with very strong auxeticity. In contrast to the known two-dimensional materials, we find that Poisson's ratio is negative in all crystal directions. In addition, the d-phase carbon monochalcogenides turn out to be direct or quasi-direct bandgap semiconductors with impressive absorption of solar radiation.

Automated summary

The two-dimensional delta-phase carbon monochalcogenides exhibit very strong auxetic properties, with negative Poisson's ratio in all crystal directions. Furthermore, they are direct or quasi-direct bandgap semiconductors with impressive absorption of solar radiation.