Transformations of the small particle Mossbauer spectra under the paramagnetism-induced superparamagnetism phase transition induced by the applied magnetic field are considered. The magnetic properties of an ensemble of small particles near the Curie point are described using the molecular field theory combined with the Langevin model. Relaxation absorption curves have been numerically simulated with the use of the two-level model. The suggestion is made that the appearance of characteristic relaxation "wings" in the M$\stackrel{..}{o}$ssbauer spectra may be an evidence of the transition of particles into the state of induced superparamagnetism.
Department of General Physics, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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