Magnetic Properties and Crystalline Fields in YbPd3

Mössbauer-effect studies of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ in the cubic intermetallic Yb${\mathrm{Pd}}_3$ at temperatures 1.4-4.2 K and in external fields up to 44 kOe yield the following results: (a) Although the Yb ion is trivalent, no magnetic ordering is seen down to 1.4 K. (b) The temperature and field dependence of the magnetic hyperfine field and the induced electric field gradient show that the ground state in the presence of external field is not an isolated level. (c) All experimental observations can be reproduced by a cubic-crystalline-field calculation with parameters $A_4〈r^4〉=-12\mathrm{}\pm 1$ ${\mathrm{cm}}^{-1\mathrm{}}$ and $A_6〈r^6〉=0.6\mathrm{}\pm 0.6$ ${\mathrm{cm}}^{-1\mathrm{}}$. These give a ${\Gamma }_7$ ground state with ${\Gamma }_8$ and ${\Gamma }_6$ lying at 29 and 39 ${\mathrm{cm}}^{-1\mathrm{}}$. These results are compared to predictions of a simple-point-charge-model calculation. Low-field spectra have been analyzed to give an ionic-spin-relaxation time ${\tau }_R\simeq 4\times {10}^{-11\mathrm{}}$ sec.