  Noncollinear antiferromagnets with novel magnetic orders, vanishingly small
net magnetization and exotic spin related properties hold enormous promise for
developing next-generation, transformative spintronic applications. A major
ongoing research focus of this community is to explore, control, and harness
unconventional magnetic phases of this emergent material system to deliver
state-of-the-art functionalities for modern microelectronics. Here we report
direct imaging of magnetic domains of polycrystalline Mn3Sn films, a
prototypical noncollinear antiferromagnet, using nitrogen-vacancy-based
single-spin scanning microscopy. Nanoscale evolution of local stray field
patterns of Mn3Sn samples are systematically investigated in response to
external driving forces, revealing the characteristic "heterogeneous" magnetic
switching behaviors in polycrystalline textured Mn3Sn films. Our results
contribute to a comprehensive understanding of inhomogeneous magnetic orders of
noncollinear antiferromagnets, highlighting the potential of nitrogen-vacancy
centers to study microscopic spin properties of a broad range of emergent
condensed matter systems.
