Chemical Tuning of Magnetic Properties through Ru/Rh Substitution in Th 7 Fe 3 -type FeRh 6-n Ru n B 3 (n = 1-5) Series

The new quaternary boride series FeRh Ru B (n = 1-5) was synthesized by arc melting and characterized by powder and single-crystal X-ray diffraction (XRD), energy-dispersive X-ray analysis, and superconducting quantum interference device magnetometry. Single-crystal structure refinement showed the distribution of the iron atoms in two of three possible crystallographic 4d metal sites in the structure (Th Fe -type, space group P6 mc). Rietveld refinements of the powder XRD data indicated single-phase synthesis of all the members. A linear decrease of the lattice parameters and the unit cell volume with increasing Ru content was found, indicating Vegard's behavior. Susceptibility measurements show decreasing Curie temperature and magnetic moment (μ ) recorded at 5 T with increasing Ru content from T = 295 K and μ = 3.35 μ (FeRh RuB ) to T = 205 K and μ = 0.70 μ (FeRhRu B ). The measured coercivities lie between 1.0 and 2.2 kA/m indicating soft to semihard magnetic materials.