Drastic Change of Magnetic Interactions and Hysteresis through Site-Preferential Ru/Ir Substitution in Sc₂FeRu_5–xIr_xB₂

The quinary members of the complex boride series Sc 2 FeRu 5– x Ir x B 2 were synthesized by arc melting the elements and characterized by powder and single-crystal X-ray diffraction as well as metallographic and energy-dispersive X-ray analyses. The use of a 4d/5d mixture allows distinguishing these elements with X-ray diffraction methods, thus enabling the study of site preference and its influence on the magnetic properties. The magnetic measurements reveal several changes of magnetic ordering within the series: from antiferromagnetism (Sc 2 FeRu 5 B 2 ) to ferromagnetism (Sc 2 FeRuIr 4 B 2 ) and finally to metamagnetism (Sc 2 FeIr 5 B 2 ). Within the quinary series, the magnetic moments continuously increase with increasing amounts of Ir in one (8 j ) of two possible Wyckoff sites. The members with x = 2 and 3 represent the first hard magnetic borides of transition metals.