Synthesis Engineering of 2D Co3Sn2S2 with Tunable Anomalous Hall Effect.

2D kagome ferromagnetic materials serve as an exceptionally important platform for exploring spintronics and correlated quantum phenomena. However, the controllable synthesis of non-layered kagome ferromagnetic materials remains a significant challenge due to the absence of van der Waals gap. Here, it is shown that ultrathin non-layered 2D Co₃Sn₂S₂ single crystal with kagome lattice, which owns strong ferromagnetic order and giant anomalous Hall effect (AHE), is obtained through flux transformation mechanism, where ultrathin Co₃Sn₂S₂ single crystal is transformed from ultrathin layered intermediates of SnS₂ or SnS. Magnetotransport measurements indicate that the AHE of the ultrathin Co₃Sn₂S₂ single crystal is superior to those of its bulk and ultrathin polycrystalline counterparts. Further, combining dimensionality advantages and the introduced extrinsic contribution of Fe, where the doping concentration can be well controlled in 2D Co₃Sn₂S₂, a giant anomalous Hall angle of 48% and an anomalous Hall conductivity of 2200 Ω^-1 cm^-1 are achieved. Under zero magnetic field, these two values are, to the best of knowledge, almost the highest ever recorded than in most known magnetic materials. The results establish 2D non-layered ferromagnetic kagome lattice as a platform for exploration of quantum confinement effect and other correlated phenomena.