Spin relaxation rate calculation due to spin-spin interaction assisted by spin-phonon interaction or vice versa in Fe3+ (3d5, 6S) ions

In this paper the mixed relaxation process is applied on paramagnetic Fe3+ (6S) ions and considering eigenvalues and eigenfunctions of three Kramers spin doublets of Fe3+ (6S) ion the mixed spin relaxation rates are calculated in the temperature range of 1K to 30K and then compared with the experimental results obtained from the analysis of the Moessbauer magnetic hyperfine spectra of this system at low temperatures. By the comparison of calculated mixed spin relaxation rates with experimentally observed ones, it is concluded that at low temperatures the mixed spin relaxation process is also a competing mode for the energy exchange between electronic spin and phonons in Fe3+ (6S) ions. (author). 12 refs., 2 tabs