Crystal-field splittings in the cubic Heusler alloys HoPd/sub 2/Sn and ErPd/sub 2/Sn

Neutron inelastic scattering measurements have been taken with triple-axis and time-of-flight techniques to determine the crystal-field levels of the rare-earth ions in the cubic Heusler alloys HoPd/sub 2/Sn and ErPd/sub 2/Sn. The observed excitations have been identified as crystal field in origin by their dispersionless character as well as by the temperature and wave-vector dependence of the intensities. Analysis of the data shows that the energies and intensities can be understood on the basis of a crystalline electric field with cubic point symmetry, with Lea, Leask, and Wolf parameters of W = 0.0287(4) meV and x = 0.3248(8) for HoPd/sub 2/Sn, and W = -0.0450(4) meV and x = 0.3022(6) for ErPd/sub 2/Sn. These parameters yield the magnetic triplet GAMMA/sub 5//sup (1)/ as the ground state for holmium, with magnetic moments of ( +- 5.49,0)..mu../sub B/, while the erbium ground state is the magnetic quartet GAMMA/sub 8//sup (3)/ with magnetic moments of ( +- 6.31, +- 1.33)..mu../sub B/. The crystal-field parameters for the other rare-earth elements have also been calculated by scaling to the values determined for HoPd/sub 2/Sn.