Spin-splitting above room-temperature in Janus Mn2ClSeH antiferromagnetic semiconductor with a large out-of-plane piezoelectricity

Two-dimensional (2D) antiferromagnets have garnered considerable research interest due to their robustness against external magnetic perturbation, ultrafast dynamics, and magneto-transport effects. However, the lack of spin-splitting in antiferromagnetic (AFM) materials severely limits their potential in spintronics applications. Inspired by inherent out-of-plane potential gradient of Janus structure, we predict three stable AFM Janus Mn2ClXH (X = O, S, and Se) monolayers with spontaneous spin-splitting based on first-principles calculations. Notably, Janus Mn2ClSeH exhibits a high Néel temperature of up to 510 K, robust perpendicular magnetocrystalline anisotropy, outstanding out-of-plane piezoelectricity of 0.454 × 10−10 C/m, and sizeable spontaneous valley polarization of 17.2 meV. Moreover, the spin-splitting can be significantly enhanced through appropriate synergistic regulation of biaxial strain and external electric field. These results demonstrate that the Janus Mn2ClSeH monolayer is a very potential candidate for designing intriguing antiferromagnet-based devices with fantastic piezoelectric and valleytronic characteristics.