Achieving Large Valley Polarization in Altermagnet Semiconductor Mg(FeN)₂ Monolayer

Achieving valley polarization in altermagnets holds crucial significance for advancing the field of valleytronics. In this study, the Mg(FeN)2 monolayer is predicted as an altermagnet semiconductor with an in-plane magnetic anisotropy. Moreover, a pair of energy-degenerate valleys occurs in the present Mg(FeN)2 monolayer, which is connected by the crystalline symmetry. Two equivalent valleys can be polarized and reversed by applying an electric field along the z direction or in-plane uniaxial strain. To further enhance the valley polarization, a coordinated approach by combining both electric field and strain is proposed. Through simultaneously applying an electric field and uniaxial strain in the Mg(FeN)2 monolayer, the valley polarization could be 1.5 and 2.9 larger than that of just only applying in-plane uniaxial strain and an electric field, respectively. This coordinated regulation strategy offers a promising approach for precise valley polarization control, thereby broadening the scope for innovative valleytronics device design.