Influence of the crystalline field and Kondo effects on the relaxation rate: Application to Mössbauer experiments of ytterbium diluted in gold

Mössbauer experiments show that the relaxation rate of the doublet ground state ${\Gamma }_7$ in $Au \mathrm{Yb}$ alloys, divided by the temperature, behaves logarithmically at low temperatures and rises very quickly above 10 K. This behavior is accounted for by computing the relaxation rate up to third order in the exchange integrals, with a Hamiltonian which decribes the resonant scattering of ytterbium impurities and takes into account both spin and orbit exchange scattering and crystalline field effect.