Ionic Sliding Ferroelectricity in Layered Ion Conductors.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Sliding ferroelectricity in 2D materials shows promise but suffers from weak polarization due to van der Waals interactions.
• Asymmetric stacking in 2D bilayers and multilayers is key to sliding ferroelectricity.

Purpose of the Study:

• To propose and investigate a novel type of ionic sliding ferroelectricity in layered ion conductors.
• To overcome the limitation of weak polarization in existing sliding ferroelectric systems.
• To explore the unique switching mechanisms and multiferroic properties of ionic sliding ferroelectricity.

Main Methods:

• First-principles calculations to investigate the electronic and structural properties of layered ion conductors.
• Theoretical modeling of layer translation and ion displacement effects on polarization.
• Analysis of the interplay between ferroelectricity, ionic motion, and altermagnetism.

Main Results:

• Identified a new mechanism of ionic sliding ferroelectricity in layered ion conductors with enhanced vertical polarization (order of magnitude increase).
• Demonstrated reversible polarization switching via in-plane layer and ion translation.
• Revealed intercorrelated switching of vertical polarization with layer sliding and ion displacement, potentially leading to quantized or fractional switching.
• Provided first-principles evidence for coexisting ionic sliding multiferroicity with altermagnetism.

Conclusions:

• Ionic sliding ferroelectricity in layered ion conductors offers a pathway to overcome polarization limitations of 2D sliding ferroelectrics.
• The discovered switching mechanisms present opportunities for novel quantum ferroelectric phenomena.
• The coupling between ionic ferroelectricity and altermagnetism opens avenues for multiferroic applications with tunable spin properties.