Alloying two-dimensional VSi₂N₄ to realize an ideal half-metal towards spintronic applications

Modulating the electronic properties of VSi₂N₄ with high Curie temperature to realize an ideal half-metal is appealing towards spintronic applications. Here, by using first-principles calculations, we propose alloying the VSi₂N₄ monolayer via substitutive doping of transition metal atoms (Sc-Ni, Y-Mo) at the V site. We find that the transition metal atom (except the Ni atom) doped VSi₂N₄ systems have dynamical and thermal stability. The doping of transition metal atoms can modulate the electronic structure of VSi₂N₄. Especially, the doping of the Sc/Y atom transforms VSi₂N₄ into an ideal half-metal, while the doping of the Ti/Zr atom leads to a half-semiconductor. For the half-metallic Sc- and Y-doped VSi₂N₄ devices, the magnetoresistance ratios up to 10¹⁰% and 10⁸% are achieved, respectively. When the magnetization direction is parallel, the spin filtering efficiency of both devices reaches up to 100% at a low bias voltage, independent of the bias direction. When the magnetization direction is antiparallel, both show a dual spin filtering effect. Our findings offer a theoretical reference for modulating the electronic properties of two-dimensional materials towards spintronic applications.