Dzyaloshinskii-Moriya interaction engineering for field-free ultra-small skyrmions in alkali-functionalized monolayer Cr2Te3

Abstract

The Dzyaloshinskii-Moriya interaction (DMI), originating from spin-orbit coupling and inversion-asymmetry, plays a crucial role in stabilizing topological magnetism (e.g., skyrmions, bimerons), which emerges as a promising candidate for advanced applications in magnetic sensors, non-volatile memories, logics, and neuromorphic computing. Despite the intrinsic centrosymmetry of most two-dimensional (2D) magnets which results in vanishing DMI, surface adsorption offers a potential strategy to break this inversion symmetry and induce measurable interfacial DMI. Herein, we systematically explore DMI engineering in monolayer Cr2Te3 through alkali metal surface functionalization, where the alkali metal atom types and adsorption ratios are precisely modulated to tailor magnetic properties. First-principles calculations reveal that a substantial, layer-dependent DMI is achieved, particularly in the top and bottom magnetic Cr layers. Atomistic spin dynamics simulations further demonstrate the emergence of diverse field-free topological magnetism in these functionalized structures, including Néel-type skyrmions with an ultra-small diameter of 4 nm, chiral magnetic domain walls, and magnetic vortex-antivortex loops. This work elucidates the underlying mechanism of DMI induced by alkali-adsorption in 2D magnets and offers a universal surface engineering strategy for the rational design of next-generation high-density chiral spintronic devices.