Rare earths in UAl2: quenching of spin fluctuations?

Experimental results involving the substitution of U atoms by Gd and Dy in the spin fluctuation system UAl₂ are studied in terms of the theory proposed by Doniach and Wohlfarth. Besides the intraband f-f Coulomb interaction, the model contains the Zener coupling between localized 4f spins and itinerant 5f states. The induced effective f-f interaction increases the proximity to a magnetic instability.