Density Functional\nTheory Prediction of Room-Temperature\nTwo-Dimensional Ferromagnetic Materials for Applications as Spintronic\nDevices

Currently, two-dimensional (2D) ferromagnetic (FM) materials\nhave\nbecome one type of promising spintronic devices. However, the practical\napplications of 2D FM materials are severely hampered by low Curie\ntemperature (<i>T</i><sub>C</sub>), which emphasizes the\nurgent need to design high-temperature 2D ferromagnets. Herein, we\npredict two stable Kagome-latticed Ti<sub>3</sub>X<sub>4</sub> (X\n= S or Se) monolayers using first-principles calculations and investigate\ntheir stability, electronic structures, and magnetism. The Ti<sub>3</sub>S<sub>4</sub> monolayer is a robust FM bipolar magnetic semiconductor\nwith a band gap of 0.41 eV, and the Ti<sub>3</sub>Se<sub>4</sub> monolayer\nis a FM half metal (HM) with a band gap in the spin-down channel of\n0.44 eV. Monte Carlo simulations indicate that both Ti<sub>3</sub>S<sub>4</sub> and Ti<sub>3</sub>Se<sub>4</sub> monolayers exhibit\nabove-room-temperature <i>T</i><sub>C</sub>s of 382 and\n436 K, respectively. Interestingly, the FM–antiferromagnetic\ntransition and HM-to-semiconductor transition are found under tensile\nstrains. Our findings propose an effective platform to design promising\nFM candidates for potential spintronic devices.