Strain effects on electronic, magnetic and optical properties of FeP2 monolayer

The 2D magnetic semiconductors possess immense potential for the spintronic applications. Strain engineering offers unique advantages in modulating the intrinsic properties of 2D systems. Here, we investigate the effects of tensile strain on the electronic, magnetic, and optical properties of the penta-FeP 2 monolayer using first-principles calculations. Our results indicate that the GGA + U method predicts a semiconductor-to-metal transition in the FeP 2 monolayer under biaxial strain at ε = 4%, whereas no such transition is observed in the HSE06 method within the considered strain range. The critical strain for the transition depends on the exchange-correlation treatment, but the overall strain-induced band evolution trend remains consistent. Tensile strain significantly enhances the magnetic moment of the system, while its effect on magnetic anisotropy energy is strain-mode-dependent: increasing monotonically under uniaxial strain but decreasing under biaxial strain. More strikingly, a ferromagnetic-to-antiferromagnetic transition is observed at a critical uniaxial strain of 5%, accompanied by a monotonic decrease in Curie temperature under both straining modes. Additionally, tensile strain markedly boosts the optical absorption of the FeP 2 monolayer and effectively broadens its spectral response range. These findings provide theoretical guidelines for exploiting strained FeP 2 monolayer in multi-functional spintronic and optoelectronic devices.