Quantum Sensing and Imaging of Spin–Orbit‐Torque‐Driven Spin Dynamics in the Non‐Collinear Antiferromagnet Mn3Sn

Novel non‐collinear antiferromagnets with spontaneous time‐reversal symmetry breaking, non‐trivial band topology, and unconventional transport properties have received immense research interest over the past decade due to their rich physics and enormous promise in technological applications. One of the central focuses in this emerging field is exploring the relationship between the microscopic magnetic structure and exotic material properties. Here, nanoscale imaging of both spin–orbit‐torque‐induced deterministic magnetic switching and chiral spin rotation in non‐collinear antiferromagnet Mn3Sn films using nitrogen‐vacancy (NV) centers are reported. Direct evidence of the off‐resonance dipole–dipole coupling between the spin dynamics in Mn3Sn and proximate NV centers is also demonstrated by NV relaxometry measurements. These results demonstrate the unique capabilities of NV centers in accessing the local information of the magnetic order and dynamics in these emergent quantum materials and suggest new opportunities for investigating the interplay between topology and magnetism in a broad range of topological magnets. Quantum imaging of spin–orbit‐torque‐driven magnetic switching and chiral spin rotation in noncollinear antiferromagnet Mn3Sn films is achieved using nitrogen‐vacancy (NV) centers in diamond. Off‐resonance dipole–dipole coupling between Mn3Sn and proximate NV centers is also established, highlighting the significant potential of NV centers in diagnosing the local magnetic properties of emergent quantum materials with vanishingly small magnetic moments.