Switching current noise and relaxation of ferroelectric domains

TL;DR

This paper uses simulations to explore how ferroelectric domains switch and relax under electric fields, revealing universal noise behaviors and the influence of disorder and pinning on these processes.

Contribution

It introduces a three-dimensional model that links domain wall structure and pinning to universal switching current noise and relaxation behaviors in ferroelectrics.

Findings

Fractal switching current noise with universal behaviors identified.

Depinning of domain walls determines universality class under weak disorder.

Relaxation follows a stretch exponential decay with pinning-dependent exponent.

Abstract

We simulate field-induced nucleation and switching of domains in a three-dimensional model of ferroelectrics with quenched disorder and varying domain sizes. We study (1) bursts of the switching current at slow driving along the hysteresis loop (electrical Barkhausen noise) and (2) the polarization reversal when a strong electric field was applied and back-switching after the field was removed. We show how these processes are related to the underlying structure of domain walls, which in turn is controlled by the pinning at quenched local electric fields. When the depolarization fields of bound charges are properly screened we find that the fractal switching current noise may appear with two distinct universal behaviors. The critical depinning of plane domain walls determines the universality class in the case of weak random fields, whereas for large randomness the massive nucleation of domains in the bulk leads to different scaling properties. In both cases the scaling exponents decay logarithmically when the driving frequency is increased. The polarization reverses in the applied field as a power-law, while its relaxation in zero field is a stretch exponential function of time. The stretching exponent depends on the strength of pinning. The results may be applicable for uniaxial relaxor ferroelectrics, such as doped SBN:Ce.