Room-Temperature Ferromagnetism via Superexchange in Semiconductor (Cr4/6, Mo2/6)3Te6

Abstract Realizing ferromagnetic semiconductors with high Curie temperature T C is still a challenge in spintronics. Recent experiments have reported two-dimensional (2D) room temperature ferromagnetic metals, such as monolayer Cr3Te6. In this paper, through density functional theory (DFT) calculations, we propose a method to obtain 2D high T C ferromagnetic semiconductors through element replacement in these ferromagnetic metals. We predict that monolayer (Cr4/6, Mo2/6)3Te6, created via element replacement in monolayer Cr3Te6, is a room-temperature ferromagnetic semiconductor exhibiting a band gap of 0.34 eV and a T C of 384 K. Our analysis reveals that the metal-to-semiconductor transition stems from the synergistic interplay of Mo-induced lattice distortion, which resolves band overlap, and the electronic contributions of Mo dopants, which further drive the formation of a distinct band gap. The origin of the high T C is traced to strong superexchange coupling between magnetic ions, analyzed via the superexchange model with DFT and Wannier function calculations. Considering the fast developments in fabrication and manipulation of 2D materials, our theoretical results propose an approach to explore high-temperature ferromagnetic semiconductors derived from experimentally obtained 2D high-temperature ferromagnetic metals through element replacement.