Two-dimensional single-layer ferrimagnetic TiMnX2 and TiCoX2: First-principles calculations and Monte Carlo simulations

Two-dimensional single-layer intrinsic magnetic materials have the characteristics of high surface activity and easy regulation, making them a popular material in current spintronics. This article uses density functional theory (DFT) to systematically study the two-dimensional monolayer TiMnX${}_2$ (X=S, Se) and TiCoX${}_2$ (X=S, Te). All structures are stable and 100% spin-polarized. Based on the Heisenberg model, combined with interaction parameters and magnetic anisotropy energy, we used the Monte Carlo method to calculate the Neel temperatures of two-dimensional single-layer TiMnX${}_2$ and TiCoX${}_2$, which were 240 K, 280 K, 100 K, and 180 K, respectively. Finally, strain control was applied to these four materials, and the materials’ half-metallicity and Neel temperature changes under lattice deformation conditions were calculated. Among them, TiMnX${}_2$ (X=S, Se) two materials had Neel temperatures higher than 300 K (room temperature) under 3% deformation. These findings provide four competitive ferrimagnetic candidate materials for single-layer spintronics materials.