High-Temperature Moiré Magnetism in Twisted Itinerant Ferromagnets.

Moiré superlattice in twisted van der Waals (vdW) magnets provides a powerful route to engineer interlayer magnetic exchange interactions and emergent magnetic states. While moiré-induced magnetism has been extensively explored in antiferromagnetic (AFM) insulators, its realization in ferromagnetic (FM) metals remains a challenge due to the presence of itinerant electrons and competing magnetic energy scales, which together weaken or obscure the effect of magnetic moiré potential, particularly at high temperatures relevant for spintronic applications. Here, we report the electrical identification of moiré magnetism in small-angle (0.5°) twisted Fe3GeTe2 multilayers, persisting up to 160 K. By leveraging the anomalous Hall effect and magnetoresistance as sensitive probes, we observe a characteristic multistep magnetization reversal, in sharp contrast to the single switching of untwisted samples, which serves as a fingerprint of a mixed magnetic state landscape. Supported by polar magneto-optical Kerr effect microscopy and micromagnetic simulations, we attribute these signatures to the coexistence of AFM and FM domains spatially locked by the long-wavelength moiré superlattice. Upon cooling, the relative weight of AFM domains is compressed due to the competition between the magnetic moiré potential and the strengthening perpendicular magnetic anisotropy. These results demonstrate high-temperature moiré magnetism in vdW metallic ferromagnets and establish twist engineering as an effective approach to control magnetic states.