MODEL FOR NONEXPONENTIAL NUCLEAR-RELAXATION IN HIGHLY DOPED MAGNETIC GLASSES

NMR measurements on rare-earth metaphosphate glasses, made over a wide temperature range, have shown that nuclear relaxation is not governed by a single exponential in these systems. A model that incorporates s pin diffusion ideas has been developed to explain the results. For the highly doped paramagnetic glass systems, it appears that nuclear spin s contributing to the NMR signal are found in distinct regions, which are distinguished by the presence or absence of spin diffusion amongst the nuclear spins. The model satisfactorily accounts for the observat ions and should be applicable to other paramagnetic systems. Informati on on the rare-earth-ion spin dynamics may be obtained from the NMR me asurements using expressions derived from the model.