Self-trapped carrier states and dielectric hysteresis in disordered dipole systems

Abstract

Theory of self-trapped free-carrier states (fluctuons) at polarization fluctuations in KTaO3:Li,Nb-type disordered ferroelectrics has been developed. The main characteristics of the fluctuon, viz. its energy, localization length, effective mass, and mobility have been calculated as functions of impurity-dipole concentration and temperature. The theory predicts the appearance of stable fluctuon states both in the ferroelectric-dipole-glass mixed phase and in the dipole glass state of disordered ferroelectrics. The possible participation of fluctuons in conduction and other transport phenomena in disordered ferroelectrics is discussed.