Rational synthetic tuning between itinerant antiferromagnetism and ferromagnetism in the complex boride series SC2FeRu5-nRhnB2 (0≤n≤5)

Single crystals of the complex boride series Sc(2)FeRu(5-n)Rh(n)B(2) (n = 1, 3, 4) were synthesized by arc-melting the elements in water-cooled copper crucibles under argon atmospheres and were chemically characterized by single-crystal XRD and EDX analyses. The new compounds are isotypic and crystallize in the tetragonal space group P4/mbm with Z = 2, adopting a substitutional variant of the Ti(3)Co(5)B(2)-type structure. The magnetically active iron atoms are arranged in chains with intra- and interchain distances of about 3.02 and 6.60 angstrom, respectively. Strong ferromagnetic interactions are observed for both Sc(2)FeRuRh(4)B(2) (64 valence electrons (VE), T(c) approximate to 350 K, mu(a) = 3.1 mu(B)) and Sc(2)FeRu(2)Rh(3)B(2) (63 VE, T(c) approximate to 300K, mu(a) = 3.0 mu(B)), whereas antiferromagnetic interactions are found in the case of Sc(2)FeRu(4)RhB(2) (61 VE, T(N) approximate to 10K, mu(eff) = 3.2): The magnetism of the entire Sc(2)FeRu(5-n)Rh(n)B(2) (0 <= n <= 5) series is discussed based on the variable valence-electron count and the resulting Fe-Fe bonding character, and it is also compared with other isoelectronic systems.