Hyperfine interactions of Sm and Co inSm2Co17

Abstract

The Sm and Co hyperfine fields in ${\mathrm{Sm}}_{2}$${\mathrm{Co}}_{17}$ have been measured at 4.2 K by means of the zero-field NMR spin-echo technique. The Sm resonance shows the existence of the ${\mathrm{Th}}_{2}$${\mathrm{Ni}}_{17}$-type structure with two inequivalent sites for the Sm nucleus having hyperfine fields of 3.40 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ and 3.48 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ G. It also shows that the effect of the mixing of the excited $J=\frac{7}{2}$ level into the ground $J=\frac{5}{2}$ multiplet by crystal- and exchange-field effects had a smaller effect on the hyperfine interaction than was expected. The hyperfine fields of the $^{59}\mathrm{Co}$ resonance show a broad distribution from 110 to 220 MHz which we were able to correlate to the number of neighboring Co and Sm atoms surrounding the site in question.