A new double-layered kagome antiferromagnet ScFe6Ge4

ScFe6Ge4 with the LiFe6Ge4-type structure (space group Rm), which has a double-layered kagome lattice (18h site) of Fe crystallographically equivalent to that of a well-known topological ferromagnet Fe3Sn2, is newly found to be antiferromagnetic (AFM) with a high Néel temperature of TN ≈ 650 K, in contrast to the ferromagnetic (FM) ground state previously proposed in a literature. 45Sc nuclear magnetic resonance experiment revealed the absence of a hyperfine field at the Sc site, providing microscopic evidence for the AFM state and indicating AFM coupling between the bilayer kagome blocks. The stability of the AFM structure under the assumption of FM intra-bilayer coupling is verified by DFT calculations.