Magnetic properties of MgFe6Ge6

We investigate the magnetic properties of the HfFe6Ge6-type MgFe6Ge6 compound from DC magnetic measurements, powder neutron diffraction and 57Fe Mössbauer spectroscopy. MgFe6Ge6 magnetically orders at TN=501 K. No metamagnetic transition is detected in fields up to 9 T. The magnetic structure is built upon ferromagnetic (001) Fe planes antiferromagnetically (+ -+-) stacked along the c-axis with the Fe moments pointing along the c-axis. The saturated Fe moment refines to mFe=1.59μB and the hyperfine field at the iron nucleus is found to be H=170 kG at 5 K. Both the low temperature susceptibility data and the 57Fe Mössbauer spectra point to deviations to the ideal easy-axis antiferromagnetic behavior. The results are discussed and compared to previously published data concerning other RFe6Ge6 involving a non-magnetic R.