Neutron Diffraction Study On Hp 13 Type M7-Xmnxge6 (M = Co, Fe)

We have made neutron diffraction experiments for Fe7-xMnxGe6 with x = 2 and 4 and CO7-xMnxGe6 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 Fe3Mn4Ge6 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 mu(B)/(Mn or Fe) atom, respectively. Magnetic structures of the other alloys are quite complicated. (C) 1998 Elsevier Science B.V. All rights reserved.