The Sm magnetic hyperfine field in Sm${\mathrm{Co}}_5$ has been measured at 4.2° K using the NMR technique and is found to be 3.42 × ${10}^6$ G. The effects on the hyperfine interactions and magnetic moment of the mixing of excited $J$-levels into the ground $J=\frac{5}{2}$ multiplet are discussed and are found to be appreciable.

• Received 8 July 1975

DOI:https://doi.org/10.1103/PhysRevB.12.4653