Abstract
The Preisach model has been a cornerstone in the fields of ferromagnetism and ferroelectricity since its inception. It describes a real, non-ideal, ferroic material as the sum of a distribution of ideal ‘hysterons’. However, the physical reality of the model in ferroelectrics has been hard to establish. Here, we experimentally determine the Preisach (hysteron) distribution for two ferroelectric systems and show how its broadening directly relates to the materials’ morphology. We connect the Preisach distribution to measured microscopic switching kinetics that underlay the macroscopic dispersive switching kinetics as commonly observed for practical ferroelectrics. The presented results reveal that the in principle mathematical construct of the Preisach model has a strong physical basis and is a powerful tool to explain polarization switching at all time scales in different types of ferroelectrics. These insights lead to guidelines for further advancement of the ferroelectric materials both for conventional and multi-bit data storage applications.
Highlights
The Preisach model has been a cornerstone in the fields of ferromagnetism and ferroelectricity since its inception
Based on the experimental observations, we show that the combination of the Preisach model, the thermally-activated nucleation-limited switching (TA-NLS) formalism, and the adapted Kolmogorov–Avrami–Ishibashi (KAI-NLS) theory provides a full and consistent description of the macroscopic ferroelectric devices in terms of device nanostructure and energetic disorder
These insights generally apply to any ferroelectric material of polycrystalline and semi-crystalline structure, including inorganic ones
Summary
Being able to address different parts of the PD, we will measure the experimental switching kinetics of discrete PD sections For this we use a measurement protocol with the pulse signal sequence as shown, which gives us log-normal switching current transients for each point in the Preisach plane at the same constant applied field. This constant switching time (blue full circles in Fig. 6b) sits close to the minimum value obtained from the measurement mode A This tells that the switching time is at its minimum if hysterons with the smallest coercive field value—good nucleation sites corresponding to U ≈ 0—are available, no matter which fraction of the PD is switched.
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