Crystal field of Dy implanted in Ag obtained by Mössbauer spectroscopy

The magnetic field dependence of the hyperfine interaction of ${}_{}{}^{161}{}_{}{}^{}\mathrm{Dy}$ impurities in Ag has been studied in external fields up to 3.2 T by means of Mössbauer spectroscopy. ${}_{}{}^{161}{}_{}{}^{}\mathrm{Dy}$ was introduced into a single crystal of Ag by means of low-temperature implantation. From the measurements we can determine the parameters of the cubic crystalline electric field (CEF) acting on the Dy nuclei: $A_4〈r^4〉=-13.5\mathrm{}\pm 4.5$ K and $A_6〈r^6〉=+5.7\mathrm{}\pm 0.3$ K. These results seem to be at variance with those of other methods. However, we will show that the above CEF parameters can account for the other experimental results as well. It may be concluded that in this case Mössbauer spectroscopy is probably the only method to determine the CEF parameters $A_4〈r^4〉$ and $A_6〈r^6〉$ with reasonable accuracy.