Magnetic Construction Set: Unexpected Flexibility of Atomic Layers ⚡ экспресс

Single crystals of orthorhombic compounds RFe$$_6$$Ge$$_6$$ (R = Y, Dy, Tb) were grown, derived from the hexagonal prototype by replacing every other R atom with a Ge$$_2$$ dimer. This leads to an orthorhombic distortion of the kagome lattice with three inequivalent Fe sites. The magnetic sublattices of Fe and R order independently: Fe forms ferromagnetic kagome layers with antiferromagnetic stacking above 400 K, while the rare-earth moments order below 9 K. TbFe$$_6$$Ge$$_6$$ shows one magnetic transition, whereas in DyFe$$_6$$Ge$$_6$$ two transitions are observed, caused by crystal field effects on Dy$$^{3+}$$ ions. DFT calculations show that the ferromagnetism of the Fe planes is supported by a high density of states at the Fermi level, and reveal three energy scales: the R–Ge$$_2$$ alternation in chains is rigidly fixed, chain alignment requires less energy, and the two-dimensional ordering of anti-aligned chains costs almost nothing. These compounds open new opportunities for studying the relationship between lattice geometry and electronic and magnetic properties.