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.