Giant Carrier Mobility in a Room-Temperature Ferromagnetic VSi₂N₄ Monolayer

Using density functional theory (DFT), we investigate that two possible phases of VSi₂N₄ (VSN) may be realized, one called the "H phase" corresponding to what is known from calculation and herein the other new "T phase" being stabilized by a biaxial tensile strain of 3%. Significantly, the H phase is predicted to display a giant carrier mobility of 1 × 10⁶ cm² V^-1 s^-1, which exceeds that for most 2D magnetic materials, with a Curie temperature (T_C) exceeding room temperature and a band gap of 2.01 eV at the K point. Following the H-T phase transition, the direct band gap shifts to the Γ point and increases to 2.59 eV. The Monte Carlo (MC) simulations also indicate that T_C of the T phase VSN can be effectively modulated by strain, reaching room temperature under a biaxial strain of -4%. These results show that VSN should be a promising functional material for future nanoelectronics.