Borisenko A. Tunnelling effects in amorphous solids

The dissertation is devoted to extension of the standard tunnelling model for low-temperature phenomena in amorphous solids. A new model for amorphization kinetics under electron irradiation is proposed, in which the growth rate of amorphous precipitate consists from contributions both from relaxation of unstable atomic configurations, excited by electrons, and from diffusion flux through the interphase boundary, where the contribution from tunnelling effects is taken into account. A theory for collective dipole interaction between tunnelling two-level systems is elaborated in the mean random field approximation and an interaction-renormalized expression for density of states of the ensemble is derived. For the first time the possibility of existance of hole-compensated impurity centres [FeO4]0 in quartz glasses is theoretically predicted and, in the frame of an original model of paramagnetic tunnelling systems proposed, the low-temperature thermodynamic properties of an ensemble of such centres are described. Key words: tunnelling two-level system, paramagnetic tunnelling system, mean random field, amorphization, double-well potential, interphase boundary.