RELAXATION DUE TO INCOHERENT TUNNELING IN DIELECTRIC GLASSES

A new relaxation mechanism is shown to arise from overdamped two-level systems above a critical temperature T almost-equal-to 5 K, thus yie lding an explanation for experimental observations in dielectric glass es in the temperature range below the relaxation peak. Using the distr ibution function of the tunnelling model for the parameters of the two -level systems, both the linear decrease of the sound velocity and the linear increase of the absorption up to the relaxation maximum, are q uantitatively accounted for by our theory.