Dielectric properties of Rb₂ZnBr₄: Phase transition splitting and two modes of polarization reversal

Abstract

In an applied biasing electric field, new phenomena have been observed in Rb₂ZnBr₄ crystals. The phase transition from the incommensurate to ferroelectric phase (and vice versa) splits into two, as shown by permittivity data. In the ferroelectric phase, the polarization reversal process may proceed in two distinctly differing modes, one leading to smooth and narrow P(E) curves, the other one to a wide step-like loop with a small and well-defined number of steps. Both phenomena are tentatively explained as being due to the interaction of a defect density wave with the incommensurate modulation wave and with the collectively moving domain walls, resp.