Crystal field in some light rare-earth compounds with the cubic CsC1 structure

Neutron spectroscopy experiments were performed on the cubic CsC1-type rare-earth intermetallics Pr_.25La_.75Mg, Pr_.25La_.75Zn, Nd_.25La_.75Mg and Nd_.2La_.8Zn. Crystal field parameters were deduced, but some ambiguities remain. A neutron diffraction study of PrMg is also reported : PrMg is an antiferromagnet with a moment μ_AF = 2.7 μ_B parallel to the propagation vector $\text{q}\text{= 0, 0,}\text{1}\text{2}\text{]}$ ; a strong quadratic distortion occurs in the ordered state, reaching $\text{c}\text{a}\text{? 1 = 1.4\%}$ at 4.2 K. The crystal field determinations on the four compounds are analyzed in relation to their magnetic properties.