Magnetic transition from antiferromagnetic CrS2 to ferromagnetic MoSe2/CrS2

We studied the atomic and magnetic structures of the two-dimensional (2D) single-layer CrS2 and double-layer MoSe2/CrS2 systems based on the first principles. In this paper, the generalized Bloch condition was used to calculate the dispersion relationship E(q) between the energy of the spin spiral and spin spiral wave vector q. The curve was fitted by the Heisenberg model, and the multiple nearest neighbor Heisenberg interaction (HBI) parameters J(1)-J(6) of the single-layer CrS2 and MoSe2/CrS2 double-layer systems were obtained. The fitted HBI parameters were used to derive the E(q) over the full Brillouin zone. The paper found that the nonmagnetic MoSe2 layer changes the magnetic structure of CrS2 from an intralayer antiferromagnetic arrangement to an intralayer ferromagnetic arrangement. The mechanism can be summarized as follows: the MoSe2 layer expands the density of states of the Cr atoms, and the electron gas in MoSe2/CrS2 is transferred from the metallic CrS2 to the semiconductor MoSe2, resulting in a reduction in the Ruderman-KittelKasuya-Yosida (RKKY) interaction of the antiferromagnetic effect in CrS2. Finally, MoSe2/CrS2 exhibits ferromagnetism. This article lays the foundation to explore the various interaction mechanisms of 2D magnetic materials, such as double exchange and RKKY exchange, for the design and search for high-Curie-temperature magnetic materials and analysis of various 2D magnetic systems.