Field and temperature dependence of electronic states populations and spin relaxation in Mössbauer absorption spectra of LiNbO3:57Fe(III)

Single crystal LiNbO3:57Fe(III) Mossbauer absorption spectra at 3 Tesla and 120...300K can be fitted using a dynamical spin Hamiltonian according to spin-lattice relaxation. At high fields (0.9...7 Tesla) and 4.2K the spectra can be fitted using an electronuclear spin Hamiltonian. The area of the subspectra due to each electronic state is not in accordance with a Boltzmann distribution at the bath temperature. From the population we calculate spin temperatures which depend linearly on the external magnetic field.