First-Principles Study of Electronic, Magnetic, and Optical Properties of Strain-Engineering (V, Fe) Co-Doped SnSe₂

This paper investigates the tunable properties of two-dimensional spintronics and optoelectronics through V- and Fe-doping, alongside strain engineering. Using density functional theory, we focus on the impact of V- and Fe-doping and (V, Fe) co-doping, as well as strain engineering, on the electronic and optical properties of SnSe₂. V and Fe atoms exhibit significant local magnetic moments of 2.86 µB and 3.20 µB, respectively. Our findings reveal that (V, Fe) co-doped SnSe₂ is an indirect bandgap semiconductor with a bandgap of 0.367 eV. The ferromagnetic (FM) state, driven by the interaction between V and Fe 3d orbitals and Se 4p orbitals, is notably more stable, with a relative energy difference of − 388.30 meV. Additionally, 2% biaxial strain enhances the formation and stability of this FM state. The study also identifies a red-shift in the visible absorption spectrum, coupled with a weakening of intensity, resulting from the combined effects of doping and strain. These results demonstrate a promising strategy for the development of spintronic devices based on (V, Fe) co-doped SnSe₂.