Structural and magnetic properties of REMn6Sn≈4Ge≈2 compounds (RE = Sc, Y, Nd, Sm, Gd-Tm, Lu)

The polycrystalline HfFe6Ge6-type REMn6Sn4Ge2 compounds (rare earth, RE = Sc, Y, Nd, Sm, Gd-Tm, Lu) have been characterised by X-ray diffraction and studied by magnetisation measurements. They order above room temperature into a ferromagnetic (Nd, Sm), ferrimagnetic (Gd-Ho) or antiferromagnetic (Sc, Y, Er, Tm, Lu) state. The magnetic properties significantly deviate from those of ternary stannides suggesting a weaker antiferromagnetic character of the Mn sublattice. According to the measured coercive fields, it is suggested that the magneto-crystalline anisotropy is close to that of ternary germanides. The peculiar behaviour of this series might be related to the preferential occupation of the 2(c) site by the substituted Ge atoms.