Kinetics of ferroelectric switching in unipolar (CH₃NH₃)₅Bi₂Br₁₁crystal

Abstract

Ferroelectric switching in unipolar (CH3NH3)5Bi2Br11 crystal has been studied by optical observation of the domain structure in low electric fields and switching current registration in high fields. We discuss investigations on the temporal behaviour of the electric polarization in static electric fields as well as polarization decay after removal of the electric field. The backswitching process appears to have a correlation to a defect-induced internal field in the crystal. For the interpretation of experimental data we utilize the classical nucleation and growth model of phase transformation (e.g. Avrami–Kolmogorov theory). An analysis assuming a statistical distribution of the characteristic domain growth times is proposed to explain and to find the functional form of the experimental data.

Comparison of polarization switching in ferroelectric TGS and relaxor SBN crystals

“…In such a case, the non-integer value of dimensionality n is typically obtained [10]. The retardation behavior in such real physical conditions have been explained through polarization process with a broad distribution (Gaussian distribution) of characteristic domain growth times [11], or the Lorentzian distribution of logarithmic switching times [12]. Although fitting curves (Avrami function) have given a good fitting quality for SBN crystal (figure 5), the KAI model is not applicable to the polarization reversal of SBN crystal.…”

“…In such a case, the non-integer value of dimensionality n is typically obtained [10]. The retardation behavior in such real physical conditions have been explained through polarization process with a broad distribution (Gaussian distribution) of characteristic domain growth times [11], or the Lorentzian distribution of logarithmic switching times [12].…”

Polarization relaxation in (CH3NH3)5Bi2Br11 ferroelectric crystals

“…We find a good qualitative agreement between the theoretical predictions and the results obtained from monitoring the domain structure. It is interesting to note that, while analyzing the short-time relaxation process involving a large number of relaxing domains, we obtained a more symmetrical, Gaussian distribution function of relaxation times in MAPBB crystal [7]. …”

“…In our earlier report [7] we presented an analysis of the short-time polarization retention loss in unipolar methylammonium bromobismuthate, (CH 3 NH 3 ) 5 Bi 2 Br 11 (MAPBB), based on electrical measurements (switching current registration) and optical observation of the domain structure. In usual electric measurements a large number of domains are involved in polarization reversal process.…”

“…[1]). The polarization relaxation that occurs in the absence of an external electric field is driven primarily by a depolarization field present due to the charge redistribution near the electrode thin-film interface [2][3][4] and an internal field that has been attributed to dipolar defects in the bulk of the crystal [5][6][7]. The results indicate that no significant difference exists in the polarization relaxation behavior observed in the bulk material and in thin films.…”