Dzyaloshinskii–Moriya interaction and field-free sub-10 nm topological magnetism in Fe/bismuth oxychalcogenides heterostructures

Topological magnetism with strong robustness, nanoscale dimensions and ultralow driving current density (∼ 10⁶ A/m²) is promising for applications in information sensing, storage, and processing, and thus sparking widespread research interest. Exploring candidate material systems with nanoscale size and easily tunable properties is a key for realizing practical topological magnetism-based spintronic devices. Here, we propose a class of ultrathin heterostructures, Fe/Bi₂O₂X (X = S, Se, Te) by deposing metal Fe on quasi-two-dimensional (2D) bismuth oxychalcogenides Bi₂O₂X (X = S, Se, Te) with excellent ferroelectric/ferroelastic properties. Large Dzyaloshinskii–Moriya interaction (DMI) and topological magnetism can be realized. Our atomistic spin dynamics simulations demonstrate that field-free vortex–antivortex loops and sub-10 nm skyrmions exist in Fe/Bi₂O₂S and Fe/Bi₂O₂Se interfaces, respectively. These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces, which is extremely vital for spintronics applications.