遍歴電子磁性体Fe₃Mo₃Nの磁性クラスタ化による磁性強化

抄録

Possible mechanism of the enhancement in magnetic interaction in itinerant electron magnets other than band controlling has been studied by means of the clusterization of magnetic ions in the η-carbide type compounds Fe₂AM₃X (A = Si, Ga, Ge; M = Mo, W; X = C, N) in which tetrahedral iron clusters are bridged by p-block metals. Powder X-ray diffraction analysis reveals the existence of new members of η-carbide type compounds; Fe₂GaMo₃N, Fe₂GeMo₃C, Fe₂GaMo₃C, Fe₂SiMo₃C, Fe₂GeW₃C, Fe₂GaW₃C, and Fe₂SiW₃C. Magnetism of the obtained materials were studied by means of macroscopic magnetization measurements and ⁵⁷Fe Mössbauer spectroscopy. Although the parent materials, Fe₃Mo₃N, Fe₃Mo₃C and Fe₃W₃C are weak itinerant electron magnets, we found antiferromagnetic orders with Néel temperatures higher than room temperature in Fe₂GaMo₃N, Fe₂GeMo₃C and a ferromagnetic order in Fe₂GeW₃C.