Two-dimensional magnetic materials offer exciting possibilities for spintronic applications due to their tunable properties and reduced dimensionality. In this study, we employ density functional theory-based first-principles calculations to investigate the strain-dependent magnetic and electronic properties of monolayer FeCl \(_2\) . The unstrained monolayer exhibits a robust ferromagnetic ground state with half-metallic character, and the Fe \(^{2+}\) ions remain in a high-spin configuration across the strain range of \(-5\%\) to \(+5\%\) , indicating no spin-crossover transition. The Curie temperature, estimated via a mean-field Heisenberg model, is approximately 16 K. Notably, magnetocrystalline anisotropy energy calculations reveal a strain-induced reorientation of the magnetic easy axis from in-plane to out-of-plane at around 4% tensile strain, providing a controllable handle for spintronic device design. Phonon dispersion and formation energy analyses confirm the dynamical and thermodynamic stability of the monolayer. These results highlight the potential of FeCl \(_2\) as a stable, strain-tunable platform for 2D spintronic applications. Future studies involving substrate effects, chemical doping, or heterostructure engineering may further enhance magnetic ordering and broaden the material’s applicability in low-dimensional device architectures.
