Path to finding the critical thickness for memory in thin ferroelectric films

TL;DR

This paper investigates the critical thickness at which ferroelectric thin films can reliably maintain memory, analyzing phase transitions and stability influenced by electrode screening effects.

Contribution

It introduces a detailed analysis of phase transition nature and metastability conditions in thin ferroelectric films, aiding in identifying parameters for stable ferroelectric memory.

Findings

Phase transition between sinusoidal and single domain structures is first order.

Single domain state may be metastable at all temperatures in most systems.

Finite electrode screening length influences domain formation and stability.

Abstract

The finite screening length by real metallic electrodes, albeit very small (<1A), results in finite depolarizing field that tends to split the film into domains. In very thin ferroelectric films the domain structure reduces to sinusoidal distribution of polarization considered first in the 1980s. We discuss the phase transition between this structure and a single domain state and show that it is first order, if it exists at all. The alternative possibility is that the single domain state at zero bias voltage would be metastable for all temperatures in most systems. This scenario defines a path towards solution to a problem of finding parameters of a system that can sustain the ferroelectric memory over a desired period of time.