Synchronous polarization switching at sub-coercive fields through stochastic resonance in ferroelectric thin-film capacitors

TL;DR

This paper demonstrates that stochastic resonance enables synchronized polarization switching in ferroelectric thin-film capacitors at sub-coercive voltages, with potential applications in noisy communication signal detection.

Contribution

It provides experimental and theoretical evidence that noise can induce synchronized polarization switching in ferroelectrics via stochastic resonance, and demonstrates a proof-of-concept for sub-threshold signal detection.

Findings

Optimal noise levels enhance synchronization of polarization switching.

Kramers time correlates with stochastic resonance conditions.

Successful detection of sub-threshold frequency-shift signals in noisy environments.

Abstract

Stochastic resonance (SR) is a phenomenon by which the presence of noise in a non-linear system allows for detection of a weak sub-threshold signal, or in a bi-stable system allows for sub-coercive switching between the two states. Simple theory suggests that SR occurs when the Kramers rate (rk) of the bistable system, which is a function of noise and applied voltage, is twice the drive frequency (fsignal). Here, we demonstrate the synchronous switching of polarization with a sub-coercive voltage waveform, in a thin film ferroelectric lead zirconium titanate (PZT) capacitor through SR. We employ independent figures of merit (FOM) such as cross-covariance, output power and signal-to-noise ratio to experimentally identify the optimal noise for synchronous switching. We further experimentally measure the Kramers time in the ferroelectric, and show that FOMs indeed peak near the noise predicted by the SR condition. We also model the device characteristics using the stochastic Time Dependent Landau Ginzburg (TDGL) formulation, and capture the experimentally observed polarization switching under application of sub-coercive voltage, assisted by noise. Finally, we show a proof-of-concept implementation of detecting sub-threshold frequency-shift-key signals (FSK) in noisy communication channels using our ferroelectric PZT devices.