Van vleck paramagnetism of the diluted intermetallic compounds Pr1−x Y x Ni5 at fields up to 15 T

We have measured the 16 Hz susceptibility of the diluted Van Vleck paramagnets Pr1−x Y x Ni5 withx=0.00, 0.05, 0.10. 0.20 at temperatures 1.5 K≤T≤50 K and magnetic fields up to 15T. Their Van Vleck type magnetic susceptibility χ(T, B, x) strongly depends on the field atB≥6 T. The temperatureT max(B, x) of the maximum of χ(T, B, x) decreases at increasing the field from zero to 15 T by approximately one order of magnitude for all Pr1−x Y x Ni5 compounds. Changing the dilutionx from zero to 0.20, the field whereT max(B, x) strongly drops is increased from 9 T to 11 T. Our data agree qualitatively with the predictions of a point charge model which considers the Zeeman term in addition to the electronic exchange and the dominating crystal field contributions.