Charged ferroelectric domain walls for deterministic a.c. signal control

TL;DR

This study uncovers how charged ferroelectric domain walls in ErMnO3 respond to alternating currents, enabling reversible switching of output signals and opening new avenues for nanoelectronic applications.

Contribution

It reveals the distinct a.c. response of charged ferroelectric domain walls and demonstrates voltage-controlled reversible switching of signal types.

Findings

Charged domain walls exhibit non-linear a.c. responses.

Reversible switching between uni- and bipolar signals is achieved.

Response depends on the domain-wall charge state.

Abstract

The direct current (d.c.) conductivity and emergent functionalities at ferroelectric domain walls are closely linked to the local polarization charges. Depending on the charge state, the walls can exhibit unusual d.c. conduction ranging from insulating to metallic-like, which is leveraged in domain-wall-based memory, multi-level data storage, and synaptic devices. In contrast to the functional d.c. behaviors at charged walls, their response to alternating currents (a.c.) remains to be resolved. Here, we reveal a.c. characteristics at positively and negatively charged walls in ErMnO3, distinctly different from the response of the surrounding domains. By combining voltage-dependent spectroscopic measurements on macroscopic and local scales, we demonstrate a pronounced non-linear response at the electrode-wall junction, which correlates with the domain-wall charge state. The dependence on the a.c. drive voltage enables reversible switching between uni- and bipolar output signals, providing conceptually new opportunities for the application of charged walls as functional nanoelements in a.c. circuitry.