A promising auxetic material of CaAs_3 monolayer with anisotropic electro-mechanical and optical properties

摘要

Two dimensional (2D) auxetic materials with large negative Poisson's ratio (NPR) are highly desirable for applications in medicine, tougher composites, defense, and so on. In this paper, by using first-principles calculations, we identify that the CaAs_3 monolayer is an excellent auxetic material with large NPR value up to -0.36 along the hinges direction. The relatively small Young's modulus ranging from 23.61 to 40.50 N/m and the moderate critical strain ranging from 0.06 to 0.16 guarantee its extraordinary flexibility and moderate ductility. Owing to its unique crystal structure, the anisotropy of basic mechanical parameters, electrical conductance, and optical absorption are concentrated on the CaAs_3 monolayer. Moreover, the electric field-induced tunability of optical absorption also emerged in the CaAs_3 monolayer. All of these extraordinary properties allow 2D CaAs_3 to have great potential applications in designing electromechanical devices and photoelectric devices as well.