Embedded Three-Dimensional Bubble-Like Polar Textures with Ionic-Ordering-Assisted Stabilization in CuInP₂S₆.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Stabilizing three-dimensional (3D) bubble-like polar textures in ferroelectrics is crucial for high-density memory and neuromorphic applications but remains a significant challenge.
• Van der Waals ferroionic crystals offer a novel platform for exploring exotic polar phenomena.

Purpose of the Study:

• To report the discovery and characterization of embedded 3D bubble-like polar textures in the van der Waals ferroionic crystal CuInP2S6 (CIPS).
• To investigate the stabilization mechanisms and electrical reconfigurability of these unique polar textures.

Main Methods:

• Utilized angle-resolved vector piezoresponse force microscopy (AR-VPFM) and tomographic piezoresponse force microscopy (TPFM) to visualize and analyze the 3D polar structures.
• Employed transmission electron microscopy (TEM) for cross-sectional imaging and to probe local atomic arrangements.
• Investigated electrical bias-induced reconfiguration of the polar textures.

Main Results:

• Successfully embedded 3D bubble-like polar textures, identified as isolated, capsule-shaped polar nanostructures within the CIPS lattice.
• Determined a center-divergent Néel-like polarization configuration and linked texture stabilization to site-selective Cu-ion occupancy and ordering.
• Observed weak size variation and reversible reconfiguration between bubble-like and quasi-single-domain states via Cu-ion redistribution under electric bias.

Conclusions:

• Ionic ordering in van der Waals ferroics provides a viable route for stabilizing and manipulating embedded 3D polar textures.
• These findings open new avenues for developing electrically reconfigurable nanoscale ferroic devices with potential applications in memory and neuromorphic computing.