Independent magnetic ordering of the rare-earth (R) and Fe sublattices in the RFe6Ge6 and RFe6Sn6 series

Magnetic ordering of the rare-earth (R) and Fe sublattices in R-Fe based intermetallic compounds is normally a cooperative phenomenon with the R and Fe sublattices ordering together - at the same temperature. We have recently studied the RFe6Ge6 and RFe6Sn6 compounds using a combination of neutron powder diffraction and Mossbauer spectroscopy (both Fe-57 and Sn-119). These series show independent magnetic behaviour of the R and Fe sublattices. The Fe sublattice orders antiferromagnetically below a Neel temperature of similar to 485 K in RFe6Ge6 and similar to 555 K in RFe6Sn6- The R sublattice orders predominantly ferromagnetically at much lower temperatures, ranging from 45 K for GdFe6Sn6 to 3 K for ErFe6Ge6, without affecting the Fe order. Here, we review neutron diffraction and Mossbauer work carried out in the study of this magnetic independence. (C) 2001 Elsevier Science BY. All rights reserved.