PARTIAL QUENCHING OF RARE EARTH MOMENT IN CUBIC LAVES INTERMETALLIC COMPOUNDS

Measurements of the low-temperature (0.1° to 1.0°K) heat capacities of several cubic Laves intermetallic compounds containing praseodymium indicate the presence of a substantial nuclear hyperfine contribution to the specific heat. It is possible to relate the magnitude of this contribution to the magnetic moment carried by the Pr3+ ion in each of the materials studied. The moments deduced in this way are PrNi2, 0.582±0.006; PrCo2, 2.18±0.05; PrAl2, 2.65±0.03 μB. These are each significantly less than the free Pr3+ ionic moment of 3.20 μB. The results are discussed in terms of a theory of Bleaney and it is concluded that the crystalline electric field is the same in PrCo2 and PrNi2, the large moment in the former being due to a larger exchange interaction. In the case of PrAl2, the data indicate an accidental degeneracy in the crystalline field ground state. © 1969 The American Institute of Physics.