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

Abstract

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 YFe_6–xCo_xGe₆. 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.