Magnetic properties of RFe12-xMox compounds with R=Y,Gd,Ho,Er versus the molybdenum content

Magnetic properties of the tetragonal RFe12-xMox compounds with R=Y, Gd, Ho, Er and for x ranging from one to three have been analysed. For compounds with Curie temperatures larger than room temperature (RT), measurements were performed on oriented powders allowing an estimate both of the easy magnetisation direction and of the magnetocrystalline anisotropy. The Fe anisotropy always favours the c-axis whereas rare earth anisotropy depends on the sign of second order Stevens factor favouring the c-axis for Ho and the basal plane for Er. Then in the latter compound spin reorientations are observed at temperatures which increase with x. In these ferrimagnetic compounds the Fe sublattice magnetisation prevails over that of the rare earth sublattice except for R=Er and x=2.5 where a compensation temperature is observed. Analysis of the Curie temperatures allows an estimate of the R-Fe and Fe-Fe exchange interactions in the different compounds. They are comparable to those determined in other 1-12 compounds and tend to increase with the Fe amount as observed in a large number of rare earth-3d transition metal materials. (orig.)