The Electronic,Mechanical,Magnetic,Optical And Magneto-Optical Properties Of Two Dimensional Tl₂S,C₃N,Blue Phosphorene And Gray Arsenene:A First-Principles Investigation

Recently,two-dimensional(2D)materials attract considerable interest due to their ex-cellent physical and chemical properties.In this paper,using the first-principles method,we investigate the exotic performances in three kinds of 2D materials.A new 2D material Tl₂S with anti-1T-MoS₂structure is predicted to be thermodynami-cally stable.It is an indirect band-gap semiconductor and has a strong absorption for ultravi-olet light,which may be useful for ultraviolet protection equipment.We demonstrate that the monolayer C₃N is a very stable indirect band-gap semicon-ductor,which is stiffer than graphene and has a more remarkable nonlinear elastic effect.Furthermore,it has a strong absorption in the visible light range,and the absorption ratio can be effectively tuned by strain.Our results show that 2D C₃N is a promising material for optoelectronic devices applications.Blue phosphorene and gray arsenene are 2D buckled honeycomb lattices,which are composed of phosphorus and arsenic atoms,respectively.Since they are predicted in 2014by the first-principles calculations,they attract enormous attention due to their excellent elec-tronic and optoelectronic performances.Using the first-principles calculations,we theoreti-cally predict the Mexican-hat-like dispersion near the top of the valence band in blue phos-phorene and gray arsenene and the corresponding van Hove singularity of the density of state,which often results in the Stoner electronic instability and the ferromagnetic states can be established by introducing a tiny hole doping.Therefore,the ferromagnetic states are gate-tunable experimentally.We demonstate that the magnetic moment gradually decreases to zero as the nanosheet thickness increases.We then systematically investigate the magneto-optical Kerr and Faraday effect in hole-doped monolayer and bilayers blue phosphorene and gray arsenene.The results show that the magneto-optical effects not only can be gate-tunable,but also strongly depend on the nanosheet thickness,substrate,strain and spin polarization direction.Our results indicate blue phosphorene and gray arsenene the promising materials for magneto-optical device applications.