Generating Ferromagnetic Kagomé Metal by Magnetic Phase Boundary Mapping in the YFe₆Ge₆–YCo₆Ge₆ System

We demonstrate the possibility to generate itinerant ferromagnetism on a kagomé lattice by varying the structural parameters and valence electron concentration between antiferromagnetic YFe6Ge6 and paramagnetic YCo6Ge6. The substitution of Co for Fe in orthorhombic YFe6Ge6 leads to the gradual suppression of the antiferromagnetic ordering temperature in YFe6–xCoxGe6. At a higher Co content, x ≥ 4, ferromagnetic-like behavior is observed along with the change in the symmetry to the hexagonal YCo6Ge6-type structure. Finally, the magnetic ordering is completely suppressed in YCo6Ge6. Density-functional theory calculations reveal that the suppression of magnetic ordering is caused by the filling of 3d states in the band structure of these materials. This work suggests the pathway to discover new ferromagnetic kagomé metals by judicious variation of the electronic band structure via the control of valence electron concentration.