Exploring the Structural and Electronic Diversity of Layered Mg–Mn–Te Ternary Compounds: A Density Functional Theory Study

We present a first-principles investigation of the layered ternary manganese tellurides MgMnTe2, Mg3MnTe4, and MgMn3Te4 using density functional theory with GGA and meta-GGA functionals. The optimized tetragonal structures (space group No. 115) satisfy the Born elastic stability criteria, with the structural derivatives exhibiting enhanced ductility. Unlike analogous alkali-based half-metals, these systems emerge as ferromagnetic semiconductors featuring substantial energy gaps in both spin channels. The calculated total spin magnetic moments are strict integers (5 μB for MgMnTe2 and Mg3MnTe4; 15 μB for MgMn3Te4), driven predominantly by localized Mn d-states. Although advanced meta-GGA functionals modulate the magnitude of the predicted band gaps, the overarching electronic topology and magnetic character remain highly consistent. Ultimately, their calculated elastic response and intrinsic ferromagnetic semiconducting behavior identify these phases as candidates for further theoretical and experimental investigation for spintronic applications.