Tunneling electric dipole defects in insulating glass

A theoretical study of the dynamics of the two-level systems (TLS) interacting both, with each other and with "lattice" vibrations in glass is presented. The spectrum and damping of the collective excitations is calculated. The frequency dependence and concentration one of phonon lifetimes are analysed. It is shown that one of the collective modes becomes soft signalizing about spin-glass-like phase transition in insulating glass. The theory of resonance phonon scattering by the two-level systems in glass has been developed with taking into account the strong coupling of the TLS with acoustic vibrations and strong interaction between TLS. (C) 1999 Elsevier Science B.V. All rights reserved.