Effect of thermally activated dynamics on electron spin–lattice relaxation in glasses

Thermally activated dynamics of double-well systems is reexamined as a possible mechanism of electron spin–lattice relaxation (SLR) of paramagnetic centers in glasses. Using the soft-potential model, we have found that this mechanism can explain a nearly quadratic temperature dependence of the SLR rate in various amorphous materials over the temperature range 1–100 K. This mechanism is expected to be operative over this temperature range, as opposed to the phonon-induced tunneling of two-level systems, which is usually considered as the mechanism responsible for this behavior.