Mössbauer Study of Paramagnetic Relaxation in Dysprosium Ethyl Sulfate

The Mössbauer effect of the 26.5-keV $\gamma$-ray transition of ${\mathrm{Dy}}^{161}$ has been employed to study relaxation effects in dysprosium ethyl sulfate. The relaxation times determined from the Mössbauer spectra, while showing a typical exponential temperature dependence, were found to be faster than the corresponding rates extrapolated from the results obtained with "standard" relaxation-time measurements. Measurements employing oriented single crystals demonstrate "spin memory" of nuclear orientation during the relaxation processes: The selection rules $\Delta m_I=0\mathrm{}$ are verified for the Orbach relaxation processes.