Neutron diffraction study on hp 13 type M7-xMnxGe6 (M = Co, Fe)

Abstract We have made neutron diffraction experiments for Fe 7- x Mn x Ge 6 with x = 2 and 4 and Co 7- x Mn x Ge 6 with x = 3.25, which have the hexagonal hp 13-type structure. It is determined by the Rietvelt analysis for the nuclear reflection that the 1T 1 site is entirely occupied by Mn atoms and the 6T 2 site by Fe or Co atoms and excess Mn atoms. The magnetic reflection of Fe 3 Mn 4 Ge 6 corresponds to the collinear antiferromagnetism with alternating ferromagnetic layers in which the magnetic moments of the 1T 1 and 6T 2 sites are 2.5 and 1.8 μ B /(Mn or Fe) atom, respectively. Magnetic structures of the other alloys are quite complicated.