Magnetic properties of RFe6Ga6 compounds (R = Gd, Dy, Ho, Er, Tm)

We have studied the magnetic properties of several ternary rare-earth compo unds of the composition RFe6Ga6 (R = Gd, Dy, Ho, Er, Tm) by means of magnet ization measurements in high fields up to 35T. All these compounds cystalli ze in the tetragonal ThMn12 type of structure. This structure has three non -rare-earth sites. Previous neutron-diffraction studies have shown that the Fe and Ga atoms preferentially occupy the 8f and 8i sites, respectively. T hese two types of atoms share the 8i site. The RFe, Ga, compounds have magn etic ordering temperatures somewhat above 500 K. At 4.2 K, the net magnetiz ation is fairly small because of the mutually compensating effect of the R- and Fe-sublattice magnetizations. Under these circumstances, the high-fiel d free powder method, used by us previously, offers the possibility to stud y the intersublattice magnetic coupling in these materials. For all five co mpounds investigated, we have determined experimental values of the intersu blattice-coupling constants. Our results are discussed in terms of the syst ematics derived previously for the behaviour of the intersublattice-couplin g strength in a variety of different types of R-Fe intermetallics. (C) 2001 Elsevier Science B.V. All rights reserved.