Tunable topological magnetism in superlattices of nonmagnetic B20 systems

Abstract

We predict topological magnetic properties of B20 systems, that are organized in atomically thin multilayers. In particular, we focus on FeSi/CoSi and FeSi/FeGe superlattices with different numbers of layers and interface structures. We demonstrate that the absence of long-range magnetic order, previously observed in bulk FeSi and CoSi, is broken near the FeSi/CoSi interface, where a magnetic state with a nontrivial topological texture appears. Using the Heisenberg and Dzyaloshinskii-Moriya (DM) interactions calculated from first principles, we perform finite-temperature atomistic spin dynamics simulations for up to 2×106 spins to capture the complexity of noncollinear textures. Our simulations predict the formation of antiskyrmions in a [001]-oriented FeSi/CoSi multilayer, intermediate skyrmions in a [111]-oriented FeSi/CoSi system, and Bloch skyrmions in the FeSi/FeGe (001) system, with a size between 7 and 37 nm. These varieties of topological magnetic textures in the studied systems can be attributed to the complex asymmetric structure of the DM matrix, which is different from previously known magnetic materials. We demonstrate that through structural engineering both ferromagnetic and antiferromagnetic skyrmions can be stabilized, where the latter are especially appealing for applications due to the zero skyrmion Hall effect. The proposed B20 multilayers show a potential for further exploration and call for experimental confirmation. Published by the American Physical Society 2024