Antiferromagnetic ordering and strain effects in monolayer quadrilateral FeS₂

Two-dimensional (2D) transition metal dichalcogenides have garnered growing attention for spintronics devices due to their special atomic structure and rich physical properties. Here, we report a monolayer quadrilateral FeS_2 material with antiferromagnetic (AFM) ordering identified by particle swarm optimization (PSO) global structure search. Using first-principles calculations and micromagnetic simulations, we demonstrate that monolayer quadrilateral FeS_2 is an antiferromagnetic metal with the easy axis of the ground state along the c axis and a high Néel temperature (T_\rm N). We have further found that the magnetic moment of Fe atoms and magnetic states are strongly modulated by the biaxial strain in a range from -8% to 8%. When compressive strains of 2% and 6% are applied, easy axis rotation and T_\rm N increase occur, respectively. These findings establish a foundational framework for the development of FeS_2 -based AFM spintronics for potential high-speed device applications.