Interface-Induced Stability of Nontrivial Topological Spin Textures: Unveiling Room-Temperature Hopfions and Skyrmions

Topological spin textures such as skyrmions and hopfions provide a platform for dissipationless information transport and nonvolatile magnetic logic, yet their realization at ambient conditions remains limited by thermal instability and field-dependent initialization. We demonstrate the first observation of room-temperature hopfion–skyrmion assemblies stabilized without external magnetic fields in ferromagnet/topological insulator/ferromagnet (EuS/Bi₂Se₃/EuS) trilayers. Lorentz transmission electron microscopy directly reveals triangular skyrmion lattices encircled by hopfion rings, confirming the coexistence of 2D and 3D chiral topologies. Polarized neutron reflectometry and XMCD uncover persistent interfacial ferromagnetism up to 300 K, driven by interfacial Dzyaloshinskii–Moriya interactions and magnetic proximity coupling extending several nanometers into the topological insulator. Micromagnetic modeling quantitatively reproduces the emergent textures and maps the stability regime set by DMI strength, uniaxial anisotropy, and geometric confinement. These results reveal an interface-driven route to stabilize zero-field topological solitons at room temperature, opening opportunities for ultralow-power spintronics, reconfigurable logic, and topological quantum devices.