Abstract
The magnetisation curves of the cubic CsCl-type compounds ErZn and HoZn along the three principal symmetry directions are analysed taking into account magnetoelastic couplings and quadrupolar exchange interactions besides cubic crystal field and Heisenberg exchange. These additional second-order terms permit a good description of the anisotropy energy. The deduced coefficients are in agreement with the values necessary in the interpretation of the spin wave data in HoZn; they are consistent with other determinations such as magnetostriction and elastic constant measurements.