Ferroelectric charged domain walls (CDWs) are typically viewed as ultrathin, reconfigurable, and highly conductive two-dimensional (2D) components for nanoelectronics. The approach, which utilizes domain walls rather than domains as active elements, has established a new paradigm for nonvolatile memory and logic. The dimensional confinement of such CDWs could further increase device density and unlock novel functionalities. However, in conventional bulk crystals or thin films with 3D characteristics, the domain walls are generally perceived as necessarily 2D or quasi-2D entities.

Confining the dimensionality of CDWs requires implementation within dimensionally confined ferroelectric systems. Fluorite ferroelectric materials with an alternating polar/nonpolar subcell architecture demonstrate great potential in this context. Stabilizing domain walls within these polar layers enables their confinement to a 1D geometry. This confinement is expected to allow for domain walls with subcell-scale dimensions and ultrahigh density, yet this possibility had not been investigated.

Recently, a collaborative research team led by Professor/Academician JIN Kui-juan, Professor GE Chen and Associate Professor ZHANG Qinghua from the Institute of Physics (IOP), Chinese Academy of Sciences / Beijing National Laboratory for Condensed Matter Physics, addressed this question. They prepared freestanding thin films using pulsed laser deposition and experimentally observed one-dimensional charged domain walls in ferroelectric ZrO₂. The study revealed the subcell size of these walls (~2.55 Å × 2.71 Å) and their unique charge screening mechanism mediated by self-balanced oxygen occupation. The team also demonstrated the electric-field-driven creation, motion, and erasure of these charged domain walls.

The atomic-scale size and electric-field tunability of these 1D CDWs challenge the conventional understanding of CDWs and offer new opportunities for ultrahigh-density devices. This work establishes a foundation for domain wall nanoelectronics based on dimensionally confined CDWs, with potential extensions to other sub-unit-cell-segmented ferroelectrics.

This research entitled "Observation of one-dimensional, charged domain walls in ferroelectric ZrO₂" was published on Science.

The work was supported by the Youth Innovation Promotion Association CAS, the National Key R&D Program, and the National Natural Science Foundation of China. 

Fig. 1. Concept and realization scheme of 1D domain walls. (Image by Institute of Physics)

Fig. 2. 1D charged domain walls. (Image by Institute of Physics)

Fig. 3. Motion of 1D H-H CDWs in ZrO₂. (Image by Institute of Physics)

Fig. 4. Coupled CDW motion and oxygen transport in fluorite ferroelectrics. (Image by Institute of Physics)

Contact:
Institute of Physics, Chinese Academy of Sciences
GE Chen
Email: gechen@iphy.ac.cn

Key words:
Ferroelectricity; Domain wall; fluorite ferroelectrics

Abstract:
Researchers from the Institute of Physics discovered one-dimensional charged domain walls in fluorite ferroelectrics. The atomic-scale size and electric-field tunability of these 1D CDWs challenge the conventional understanding of domain walls and offer new opportunities for ultrahigh-density devices.