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

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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.