First-principles decoding of spin-valley-polarized H-phase TMDs: formation energies, magnetic ground states, and band engineering

Abstract

Using high-throughput GGA+U first-principles calculations we survey the formation energy, magnetic ground state and spin-valley-coupled electronic structure of 87 monolayer 2H-phase MX₂ (M = Groups-IIIB–IIB, X = S, Se, Te). A systematic group-by-group evolution is uncovered: 3d-based TMDs favor antiferromagnetic (AFM) semiconductors, 4d congeners stabilize ferromagnetic (FM) metals or bipolar magnetic semiconductors (BMSs), whereas 5d members are overwhelmingly non-magnetic metals. Thermodynamic stability (ΔH_f ≤ 0) is fulfilled for all sulfides/selenides/tellurides of Groups-IIIB–VIB and most of Groups-VIIB–VIII, whereas post-transition-metal TMDs (Groups IB–IIB) are unstable. Valley polarization is dictated by the interplay between hexagonal lattice symmetry and magnetic order: FM Group-VB VX₂ and BMS VSe₂/VTe₂ exhibit 100% spin-polarized K/K′ band edges ideal for the anomalous valley Hall effect, while AFM Group-VIB CrX₂ and Mo/WX₂ retain spin-degenerate K-point valleys suitable for reversible valleytronics. The resulting atlas provides an experimentally verifiable blueprint for wafer-scale synthesis of high-temperature FM, half-metallic or valley-polarized 2D crystals and accelerates the materialization of next-generation spin-valleytronic devices.