Giant self spin-valve effect in the kagome helimagnet

Kagome magnets can combine non-trivial band topology and electron correlations, offering a versatile playground for various quantum phenomena. In this work we propose that kagome magnets with frustrated interlayer interactions can intrinsically support a self spin-valve effect, and experimentally confirm this in the kagome helimagnet TmMn6Sn6. Under a magnetic field perpendicular to the helical axis, using magnetic force microscopy we observed stripe domains that stack strictly along the helical axis, which we attribute to the stability loss of the kagome helimagnetic state. Such a domain pattern spontaneously mimics the artificial multilayered structure in traditional spin valves, which, combined with the high spin polarization, leads to a giant magnetoresistance (GMR) ratio over 160%. This discovery opens an avenue to realize inherent spin valves in a variety of quantum magnets, and can hold promise in future spintronics. Spin valves, consisting of stacked magnetic layers with different magnetization are the essential building block of several distinct spintronic devices. Here, Xu, Liu, Zhao, Lin and coauthors propose that some Kagome magnets can exhibit a self spin-valve effect, and experimentally demonstrate this in the Kagome magnet, TmMn6Sn6.