Spin-dependent multilevel interactions at a nonmagnetic/magnetic MoSe2/VSe2 van der Waals interface and multifunctional properties

Since the theoretical and experimental demonstration of the quasibonding (QB) interactions between van der Waals (vdW) layers of two-dimensional (2D) materials, diverse effects and applications of interlayer and interface QB in vdW homo- and heterostructures have been reported. However, for vdW heterostructures (vdWHs) composed of magnetic and nonmagnetic 2D layers, the principles of interlayer QB interaction in these systems and their potential application remain to be elucidated. In the current work, by density functional theory calculations combined with crystal orbital Hamiltonian population analysis, the spin-dependent and multilevel interlayer QB (namely, orbital hybridization) in a $H\ensuremath{-}{\mathrm{MoSe}}_{2}/H\ensuremath{-}\mathrm{V}{\mathrm{Se}}_{2}$ nonmagnetic/magnetic vdWH is established, and its multifunctional properties for spintronics and spin-dependent optoelectronics are revealed. In particular, (1) the two spin channels have distinct interlayer interactions: spin-up is a two-level interaction while three energy levels are involved in spin-down; for each level, multiorbitals (mainly $s, {p}_{z}$, and ${d}_{{z}^{2}}$ orbitals) make contributions to the interlayer interaction; (2) distinct band alignment types ranging from type I and type II to a mixed type appear; and (3) the interlayer interaction makes the $\mathrm{V}{\mathrm{Se}}_{2}$ layer have better bipolar magnetic semiconductor properties. Our current work demonstrates the orbital-resolved multilevel analysis as a powerful tool for understanding the interlayer QB interaction and indicates the potential of the ${\mathrm{MoSe}}_{2}/\mathrm{V}{\mathrm{Se}}_{2}$ vdWH for multifunctional applications.