Activating Dzyaloshinskii–Moriya Interactions in 2D Ti ₂ Si through Selective Heavy-Atom Incorporation for Chiral Spintronic Nanodevices

Two-dimensional (2D) silicide monolayers are emerging nanoscale materials whose magnetic and relativistic properties remain largely unexplored. Here, we investigate how electric fields and transition-metal substitution control magnetic exchange, magnetocrystalline anisotropy, and Dzyaloshinskii–Moriya interaction (DMI) in monolayer Ti2Si using first-principles calculations. Pristine Ti2Si is identified as a dynamically stable ferromagnetic metal with in-plane magnetic anisotropy. However, its centrosymmetric bonding suppresses DMI even under strong out-of-plane electric fields. To induce chiral interactions at the nanoscale, we introduce controlled Pt and Co substitution at Ti sites to break inversion symmetry. Co enhances magnetic exchange, while Pt provides strong spin–orbit coupling (SOC), and their combined effect activates a finite DMI. A Wannier-based tight-binding model resolves the microscopic exchange pathways and distinguishes intralayer and interlayer contributions. The Pt-assisted interlayer Co–Pt–Co pathway dominates both the magnitude and sign of the total DMI. Among all investigated compositions, Pt0.5CoTi0.5Si exhibits the strongest DMI due to competing superexchange channels with opposite rotational preferences. These results demonstrate that symmetry engineering and targeted chemical substitution provide an effective strategy for controlling chiral magnetic interactions in two-dimensional silicide monolayers. Pt- and Co-doped Ti2Si nanosheets therefore emerge as tunable silicon-compatible platforms for electrically controllable chiral spin textures, ultrathin magnetic materials, and energy-efficient nanoscale spintronic devices.