Electronic and half-metallic properties of novel two-dimensional YSi2N4 monolayer by theoretical exploration

Based on the first-principles calculations, the effects of strain, interlayer modulation, atomic adsorption and electric field on the electronic structures of two-dimensional YSi2N4 monolayer were investigated. It is found that the YSi2N4 monolayer is mechanically stable and is a half-metal at equilibrium. The half-metallicity will disappear only when the tensile strain exceeds 14.5% and the compressive strain is greater than -10.0%. The modulation of bilayer distances indicates when the interlayer distance was reduced to 3.192 angstrom, the halfmetallicity disappears, and when the interlayer distance increases to 3.948 angstrom, the bilayer structure shows metallicity. The electronic structures of YSi2N4 adsorbed with H, O and F atoms in expanded supercell were discussed. The results show that YSi2N4 monolayer possesses half-metallic properties only when F atoms are adsorbed, while YSi2N4 monolayer possesses metallic properties when H and O atoms are adsorbed. When the electric field applied externally is between 0 and 0.78V/angstrom, the half-metallic properties of YSi2N4 monolayer can be maintained. The controlled electronic properties of two-dimensional YSi2N4 monolayer may open up an important avenue for exploring the next generation of spintronic devices.