Magnetic properties of RFe12-xMox compounds (R = Y, Er)

The magnetic properties of the RFe12-xMox compounds have been studied for R = Y and Er, with x ranging from 1 to 3. Increasing the molybdenum content leads to a decrease of(i) the Curie temperature, (ii) the 3d moment and (iii) the 3d anisotropy. All compounds with Y are weak ferromagnets but as the Mo content increases the shift between weak and strong ferromagnetism passes through a minimum around x = 1.5. In the erbium-based ferrimagnets, the thermal variation of the spontaneous magnetisation depends on the balance between the f and d metal magnetisations. In particular, for x = 2.5 the two sublattice magnetisations are almost equal at low temperature and a well-marked compensation point is observed around 10 K. For smaller Mo contents spin reorientations are observed at low temperature, which can be understood taking into account fourth-and sixth-order terms in the Hamiltonian of the crystalline electric field acting on erbium. (C) 1998 Elsevier Science B.V. All rights reserved.