Structural, Electronic, and Magnetic Properties of the van der Waals ScSi₂N₄/VSi₂N₄ Heterostructure: A First-Principles Study

The van der Waals (vdW) heterostructures provide advantages compared to conventional interfaces, such as a well-defined interface region, being easy to construct, and reducing the stress between their components. This work uses spin-polarized first-principles calculations to investigate the van der Waals heterostructure based on MSi₂N₄ with M = Sc or V. Isolated monolayers exhibit ferromagnetic characteristics with half-metal or semiconductor behavior, respectively. Phonon calculations also show evidence of their dynamic stability. The heterostructure is investigated by considering three different stackings: Top, T4, and H3. Our calculations demonstrate that T4 stacking is the most stable configuration. Also, the noncovalent interactions index shows that only vdW forces participate. The magnetic coupling between monolayers is investigated. Our results show that ferromagnetic and antiferromagnetic coupling could appear in the experiment. Regarding electronic properties, the vdW heterostructure is metallic when the Sc layer is under compressive strain. However, the heterostructure becomes a half-metal if VSi₂N₄ is under tensile strain. Finally, the magnetic anisotropy energy is investigated. According to the results, the heterostructure has an in-plane magnetization axis in-plane. Our findings demonstrate that the magnetic intrinsic nature of the heterostructure is suitable for its implementation in spintronic devices such as spin valves.