Abstract
A molecular field analysis has been made for the TbY alloy system, and the results relative to the initial magnetic ordering properties are discussed in terms of their implication for the heavy rare‐earth metals and for alloys with Y, Sc and La. The results indicate that the similarities and differences in these magnetic systems can be closely correlated with the crystal parameters which determine the distances between magnetic atoms in a particular metal or alloy. Ordering temperature changes that result from atomic size effect and pressure‐induced volume changes are compared and found to agree. Transition temperatures for alloys for which the axial ratios and atomic volumes are held constant are found to vary linearly with the effective spin variable. The over‐all results are found to be qualitatively consistent with an RKKY type of interaction.