Strain-Induced Magnetic Transition and Exchange Competition in a Metallic Cr 2 SbS Monolayer with High Néel Temperature

Abstract

Two-dimensional magnetic materials hold great promise for spintronic applications but often suffer from low Néel temperatures and limited tunability. Here, based on first-principles calculations, we identify a previously unexplored orthorhombic Cr2SbS monolayer with robust structural stability. The material is confirmed to be dynamically, thermally, thermodynamically, and mechanically stable. The Cr2SbS monolayer exhibits an antiferromagnetic (AFM) metallic ground state with a sizable magnetic anisotropy energy of 80 μeV per Cr atom favoring the out-of-plane direction. Monte Carlo simulations based on the Heisenberg model predict a Néel temperature as high as ~908 K, far exceeding room temperature, establishing it as one of the rare high-TN 2D magnets. Under biaxial strain from −4% to 4%, the system undergoes a transition from AFM to ferromagnetic (FM) ordering, accompanied by a reorientation of the easy magnetization axis from out-of-plane to in-plane. At −3% strain, one magnetic configuration converges to a nonmagnetic state, indicating strong competition among exchange interactions. Notably, the metallic nature is preserved across the entire strain range, while the critical temperature remains above room temperature. When a tensile strain is applied, the critical temperature can even exceed 1000 K. These combined features, including ultrahigh Néel temperature, robust metallicity, and strain-tunable magnetism, make the Cr2SbS monolayer a promising platform for next-generation spintronic devices.