Determination of the crystal-field parameters of Tm3+ in Ag by means of Mossbauer spectroscopy

Mossbauer spectroscopy has been used to measure the magnetic and electric hyperfine interactions of 169Tm nuclei in silver at 4.2K as a function of an external magnetic field in the range 0-3.2 T. The electronic ground state turns out to be a nonmagnetic singlet that is polarised by the external field. From the measured hyperfine field and quadrupole interaction the authors derive the parameters of the cubic CEF at the Tm site: A4(r4)=-6(5)K and A6(r6)=6.5(4)K. These values disagree strongly with previous susceptibility measurements on this system, but are close to the values found from Mossbauer spectroscopy on 161DyAg