MAGNETIC PHASES OF THE THULIUM-TERBIUM ALLOY SYSTEM

Early studies made on Tm-Tb alloys found a complex phase diagram for t he system. Because of the orthogonal anisotropies involved which lead to the Tb moments lying in the basal plane and the Tm moments along th e c-axis, the Tm-Tb system is particularly well suited to address the problem of the competing crystal-field and exchange anisotropies in th e heavy rare-earth metals. Neutron-diffraction studies were made on a number of alloys at the HMI, the ILL and ISIS. Careful continuous meas urement of the diffraction patterns over the experimental temperature range, 2 K < T < 300 K, has enabled us to complete the phase diagram f or the system, especially important at the Tm-rich end, and determine the lattice parameters. From the magnetic peaks we have deduced the mo dulation wave vectors at various temperatures. The results have been c orrelated with the effective exchange and Stevens' factors for the all oys. (C) 1998 Elsevier Science B.V. All rights reserved.