Probing near-interface ferroelectricity by conductance modulation of a nano-granular metal

TL;DR

This paper demonstrates that conductance measurements of nano-granular metals can non-invasively probe the temperature-dependent dielectric properties of adjacent ferroelectric layers, revealing interface effects and phase transition dynamics.

Contribution

It introduces a theoretical and experimental approach to monitor ferroelectric states via conductance changes in nano-granular metals, enabling high-resolution, non-invasive interface characterization.

Findings

Conductance of nano-granular metal correlates with ferroelectric dielectric properties.

Theoretical model reproduces conductance changes during phase transition.

Potential for nanoscale, non-invasive ferroelectric state monitoring.

Abstract

The electronic functionality of thin films is governed by their interfaces. This is very important for the ferroelectric (FE) state which depends on thin-film clamping and interfacial charge transfer. Here we show that in a heterostructure consisting of a nano-granular metal and an organic FE layer of [tetrathiafulvalene]$^{+\delta}$[p-chloranil]$^{-\delta}$ the nano-granular layer's conductance provides a sensitive and non-invasive probe of the temperature-dependent dielectric properties of the FE layer. We provide a theoretical framework that is able to qualitatively reproduce the observed conductance changes taking the anisotropy of the dielectric anomaly at the paraelectric(PE)-FE phase transition into account. The approach is also suitable for observing dynamical effects close to the phase transition. Focused electron beam induced deposition as fabrication method for the nano-granular metal guarantees excellent down-scaling capabilities, so that monitoring the FE state on the lateral scale down to 20--30\,nm can be envisioned.