MAGNETIC-FIELDS AT TA-181 NUCLEI IN LAVES PHASES OF RFE2 (R=ND, PR, SM, GD, DY, YB, LU)

By studying the perturbed angular correlations of gamma-rays emitted d uring the decay of Hf-181 impurities in the Laves phases of PrFe2, DyF e2, and YbFe2, we have investigated the magnetic hyperfine interaction between these compounds and its daughter nucleus Ta-181, and have det ermined the temperature dependence of the magnetic hyperfine fields. A t room temperature we obtained the following values of these magnetic hyperfine fields B-hf: B-hf(PrFe2) = 7.6(1) T, B-hf(DyFe2) = 15.5(5) T , and B-hf(YbFe2) = 18.8(3) T. When taken together with data obtained previously, the results of our experiments show that for Ta nuclei in the RFe2 Laves phases the values of B-hf depend strongly on whether R is a light or a heavy rare- earth element, which allows us to conclude that in these phases the value of the magnetic moment induced at the impurity Ta nuclei depends on the interatomic distance. (C) 1997 Ameri can Institute of Physics.