Room-temperature topological spin textures via cobalt substitution in a kagome antiferromagnet

Antiferromagnetic spintronics offers a compelling route toward high-density, ultrafast, and field-insensitive nanoscale devices, yet realizing electrically controllable magnetic textures at room temperature remains challenging. Existing approaches rely on extrinsic skyrmion textures or interfacial Dzyaloshinskii-Moriya interactions, lacking ground-state stability. Although Fe-doped Mn 3 Sn has demonstrated 6-spin-exchange-driven non-coplanar order, the resulting topological Hall effect vanishes above ~150 K, precluding room-temperature operation. Here we report Mn 2.7 Co 0.3 Sn single crystals in which Co substitution stabilizes an intrinsic non-coplanar spin texture persisting above 300 K. Neutron diffraction reveals a 10° spin canting and finite scalar spin chirality at 300 K, generating a topological Hall resistivity of 0.49 μΩ·cm. First-principles calculations confirm the real-space Berry-curvature origin from scalar spin chirality, distinct from the spin-orbit-coupling-dependent momentum-space mechanism. The distinct 3 d 7 electron count of Co, relative to Fe (3 d 6 ), correlates with enhanced thermal stability, demonstrating that substituent-specific electronic structure modulates the exchange landscape beyond generic electron doping. Furthermore, the topological response exhibits bond-directional strain sensitivity: c -axis compression preserves kagome symmetry and modulates the 6-spin strength, whereas ab -plane compression breaks trigonal symmetry. These findings establish substitutional chemistry as a route toward room-temperature topological antiferromagnetic devices.